cosmetics
Review
Essential of Hair Care Cosmetics
Aurora Alessandrini * and Bianca Maria Piraccini
Division of Dermatology, Department of Experimental, Diagnostic and Specialty Medicine,
University of Bologna, Bologna 40138, Italy; [email protected]
* Correspondence: [email protected]; Tel.: +39-051-214-3677; Fax: +39-051-214-4867
Academic Editors: Won-Soo Lee and Enzo Berardesca
Received: 18 July 2016; Accepted: 20 September 2016; Published: 27 September 2016
Abstract: Nowadays, hair care and style play a very important role in people’s physical aspect
and self-perception. Hair cosmetics can be distinguished into two main categories: cosmetics with
temporary effect on the hair, for example shampoos, conditioners, sprays, and temporary colors;
and cosmetics with permanent effect on the hair, such as permanent waves, relaxers, bleaches
and permanent colors. These cosmetic procedures may induce hair abnormalities. We provide an
overview on the most important characteristics of these procedures, analyzing components and
effects on the hair. Finally, we evaluated new camouflage techniques and tattoo scalp.
Keywords: hair; hair care; hair care cosmetics; hair care products; cosmetic ingredient; healthy hair
1. Introduction
Hair is a complex structure composed by many components that act as a unit, with the biological
purpose of protecting the scalp, as well as physical attractiveness to the self-perception of beauty.
Nowadays, hair care and style play a very important role in people’s lives, both for men and women,
so knowledge of hair products, mode of action, efficacy, ingredients and hair procedures has become
more relevant in dermatologists’ medical practice. The amount of money spent to enhance the hair
beauty is an indication of how much attention is given today to the hair appearance. On the other
hand, these data are emphasized in patients suffering from hair disease.
Hair cosmetics are also an important tool for increasing patient’s adhesion to scalp treatments,
according to the diversity of hair types and ethnicity.
Trueb [1] described them as “preparations intended for placing in contact with the hair and scalp,
with the purpose of cleansing, promoting attractiveness, altering appearance, and/or protecting them
in order to maintain them in good condition”.
Hair cosmetics can be distinguished into two main categories:
(1)
(2)
Cosmetics with temporary effect on the hair, for example shampoos, conditioners, sprays, and
temporary colors; and
Cosmetics that produce permanent effect on the hair shaft, such as permanent waves, relaxers,
bleaches and permanent colors.
2. Shampoos
Shampoos are the most commonly prescribed treatment for hair and scalp. In the past, soap was
the only available cleanser for the hair, while the introduction of the first non-alkaline shampoo date
back to 1933 [2].
The modern society requires many features in a formulation: a shampoo has primarily to clean
the scalp and the hair, but also has to be cosmetically pleasing, not dry out the hair, not irritate the
skin, improve hair beautification, and be less expensive.
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A shampoo consists of 10–30 ingredients [2], classified according to their different activities.
These ingredients include: (1) cleansing agents, called surfactants, that remove sebum or skin scale;
(2) conditioning agents that give softness to the hair; (3) active ingredients, for treating specific disease
s like dandruff; and (4) additives, such as preservatives, that contribute to the stability and comfort of
the product. Every ingredient is tested, officially approved and declared on the label.
Thanks to surfactant agents, a shampoo can remove dirty particles and sebum from the scalp and
from the hair shafts, but this cleansing activity has to be mild in order to avoid complete removal of the
natural oils and sebum from the skin. Modern shampoos are sensitive on skin or mucous membranes,
and the development of contact dermatitis is rare, due to the short contact time of the shampoo with
the scalp. Typical ingredients of shampoos are foaming agents and detergent agents, which prevent
the formation of insoluble soap on hair and scalp. Surfactant agents are the most important cleaning
substances of shampoos, thanks to their molecular structure. In particular, one end of the molecule
has a negative electrical charge and is soluble in water, so it does not blend with oils. The other end is
soluble in oil and grease and does not blend with water. These molecules surround the fragments of
grease localized on hair and scalp: the oil soluble parts go into the grease and the water-soluble parts
remain located outward, forming a hydrophilic mass that is totally negatively charged. The surface
of the hair shaft has negative charges, which tend to force the mass negative charges apart, resulting
in a reduction of tension between water and grease on the surface, and production of foam, which
incorporates the dirt, so that it cannot be re-deposited on the hair and scalp.
Conditioning molecules contained in shampoos combine the cleansing action with the function
to impart manageability, gloss and antistatic properties of the hair. This conditioning shampoos are
composed by fatty substances, like vegetable oils, wax, lecithin an lanolin derivatives, collagen, animal
proteins, quaternium ammonium compounds or cationic polymers (which are the main component of
the “2 in 1 shampoo”) and silicone, that reduce the friction obtained by combing the hair, and then the
risk of hair shaft damage [2].
Among other substances we can mentioned: glycerin, polyvinylpyrrolidone, propylene glycol and
stearalkonium chloride [3]. In particular, protein-derived substances have the property to be attractive
by the keratin (“substantivity”), with the result of temporarily adhere the cortex fragments together.
Additives of shampoos include ingredients that are able to control the thickness of the formulation like
citrate and lactate.
Another key consideration is shampoos pH: many of them have an alkaline pH, which causes
hair shaft swelling, predisponding the hair to the damage. A neutral pH shampoo is the best choice
for chemically treated hair from either permanent dyeing or permanent waving [3].
Other additives include UV absorbers, like benzophenone derivatives and antioxidants, like
ascorbic acid and α-tocopherol. Preservatives of shampoos prevent bacterial contamination, and
include sodium benzoate, parabens, ethylenediaminetetraacetic acid (EDTA), DMDM hydantoin and
tetrasodium EDTA.
Moreover, most shampoos contain other ingredients like colors, perfumes, pearlishing agents,
moisturizers such as natural oils and fatty acid esters, and humectants, such as glycerin and sorbitol.
“Medicated” shampoos contain active ingredients selected to treat medical conditions, mainly
seborrheic dermatitis or psoriasis. Active ingredients include ketoconazole, ciclopirox olamine, zinc
pyrithione, piroctone olamine, tar derivates, salicylic acid, selenium sulfide, poly-vinyl-pyrrolidone,
iodine complex, menthol and colloidal sulfur. The combination of cosmetic technology and medical
therapy allows the benefits of cosmetic products together with the efficacy of medical agents.
Adverse reactions to shampoos are rare. The most common one is accidental contact with the
mucous membranes, such as the nose and eye.
If patch testing to a shampoo is required, the shampoos should be diluted to form a 1%–2%
aqueous solution for closed patch testing and a 5% aqueous solution for open patch testing. False
positive reactions due to irritation can occur. Patch testing individual ingredients separately is
advisable [4].
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3. Conditioners
Most of the shampoos contain conditioning agents, but consumers often apply a conditioner after
shampooing, to minimize hair frizzing, increasing manageability and gloss of the hair. A conditioner
can therefore be used to reduce a chemical or mechanical trauma of the hair, such as permanent dyes,
bleaching, and excessive brushing.
As already mentioned, the hair shaft has negative electrical charges, while conditioning agents
have positive charges: conditioners acts by neutralizing the electrical negative charge of the hair
fiber by addicting positive charges and by greasing the cuticle, with the final result of reduce fiber
hydrophilicity [5]. Conditioners also help the raised cuticles to lie down against the hair surface, and
in this way preserve hair color and enhance its shyness and smoothness too.
Common ingredients of conditioners include mainly cationic surfactants, like cetyltrimethylammonium
chloride, behentrimonium, propyltrimonium, and stearamidopropyl dimethylamine.
Polymers, like mono and polypeptides like hydrolyzed proteins (amino acids), polypeptides
derived from collagen and polyvinylpyrrolidone (PVP), fill the hair shaft defects, creating a smooth
surface to increase shine while eliminating static electricity thanks to its cationic nature [3].
Emollients/oily compounds are composed of natural or synthetic oils, but also esters and waxes.
Jojoba oil, olive oil, or grape seed oil are some of these natural oils.
The most frequently used synthetic and active oils are silicones (e.g., dimethicone, dimethiconol,
amodimethicone and cyclomethicone). Dimethicone is the most widely used silicone in hair care
cosmetics, with the effect of protecting the hair shaft from abrasive actions.
Other conditioners components are: fatty alcohols (e.g., cetyl alcohol and stearyl alcohol), waxes
(e.g., carnauba wax and paraffin wax), gums (e.g., guar gum), salt (sodium chloride) and emulsifiers
like ethoxylated fatty alcohols (e.g., polysorbate-80 or ceteareth-20) [6].
In daily practice, hair conditioners can be used in different ways.
Instant conditioners are applied immediately after shampooing and rinsed off after few minutes,
while deep conditioners, formulated usually in creams, can remain on hair for 20–30 min with an
increase of their penetration.
Blow drying lotions are another formulation that can be left on the hair because are oil-free. They
are very useful for people with fine hair or excessive scalp sebum. A particular type of conditioner,
called hair glaze or hair thickeners conditioners, increase hair diameter by coating the hair shaft.
Similar to conditioners, they usually contain proteins.
4. Hair Color Products
4.1. Hair Dyes
In modern society, people want to change the hair color according to the fashion trends of the
moment, and thanks to developments in the field of dyestuffs, now this desire can be obtained in a few
minutes. Nowadays, hair dyes are utilized by both men and women to modify natural hair color or
restore pigmentation once graying has set in.
Modern hair dyes can be classified into three categories: temporary, semi-temporary and
permanent. The main difference between them is their capacity to reach the hair cortex, obtained by an
alkaline pH. In many of these products, ammonia or ethanolamine are addicted to increase the pH [5].
Temporary colors are applied in the form of shampoos, lotions or foam and change the hair
color for a relatively short time, normally until the first wash. They are generally used to add color
highlights, remove yellowish hues from white hair, or cover up few graying hairs.
Ingredients of temporary colors are products with a high molecular weight, which simply deposit
on the cuticle of the hair and are then removed easily. The dye is bonded to a cationic polymer to
reduce its solubility and increase its affinity to hair. The resulting complex is dispersed in a base using
surfactants to make the final product [7].
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One example is henna, obtained from the plant Lawsonia alba, which is used on skin and nails, too.
In the literature, few cases of allergic contact dermatitis to henna have been described [5,8].
Cosmetics 2016, 3, 34
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Semi-permanent colors are composed by ingredients like nitroaromatic amines or aromatic dyes
(of low molecular
weight),
which
do not
bind
the Lawsonia
hair protein
because
theyon
doskin
notand
oxidize:
One example
is henna,
obtained
from
theto
plant
alba, which
is used
nails, they
are water
soluble,
so
they
can
be
washed
out
after
usually
6–10
wash
cycles
or
earlier.
They
too. In the literature, few cases of allergic contact dermatitis to henna have been described [5,8]. do not
Semi-permanent
colors are composed
by ingredients
nitroaromatic
or aromatic
contain ammonia
or ethanolamine,
but hydrogen
peroxidelike
or resorcinol
canamines
be present.
The main
dyesof(ofsemi-permanent
low molecular weight),
do not
bindhair
to the
protein
because
they
not oxidize:
purpose
colors which
is to color
white
orhair
to give
more
tone to
thedonatural
color, but
they
are
water
soluble,
so
they
can
be
washed
out
after
usually
6–10
wash
cycles
or
earlier.
They
dothese
they cannot lighten hair. One important characteristic is low molecular weight, which enables
not contain ammonia or ethanolamine, but hydrogen peroxide or resorcinol can be present. The
products to diffuse into the middle layers of the cuticle without binding firmly to the hair protein
main purpose of semi-permanent colors is to color white hair or to give more tone to the natural
itself [9]. Consequently, the application of semi-permanent colors does not require any prior hair
color, but they cannot lighten hair. One important characteristic is low molecular weight, which
modification,
required instead by permanent hair color.
enables these products to diffuse into the middle layers of the cuticle without binding firmly to the
Permanent
hair [9].
dyeing
is a process
that permanently
changes the
color
therequire
hair, any
through
hair protein itself
Consequently,
the application
of semi-permanent
colors
doesofnot
a chemical
reaction
of
oxidation,
which
allows
the
molecules
of
color
to
penetrate
into
the hair.
prior hair modification, required instead by permanent hair color.
Permanent
colors allow
darkening
or brightening
hair color,
and are
to any
Permanent
hair dyeing
is a process
that permanently
changes
theresistant
color of the
hair,external
through afactor,
chemical
reaction for
of oxidation,
which
allows
themany
molecules
to and
penetrate
into the
including
washings,
4–6 weeks.
They
offer
rangeof ofcolor
hues
can cover
thehair.
highest
Permanent
colors
allow
darkening
or
brightening
hair
color,
and
are
resistant
to
any
external
factor,
gray-hair numbers.
including
washings,
for 4–6
weeks.
They offerofmany
range of molecules
hues and can
theofhighest
The
principle
consists
in the
penetration
the coloring
intocover
pores
hair shaft
gray-hair numbers.
(previously increased in size, by hydration and alkalinization). At this point, the molecules are
The principle consists in the penetration of the coloring molecules into pores of hair shaft
oxidized and assume color, which is transmitted to the keratin of the cuticle and the cortex, mimicking
(previously increased in size, by hydration and alkalinization). At this point, the molecules are
natural
melanin
oxidized
andgranules.
assume color, which is transmitted to the keratin of the cuticle and the cortex,
During
these
reactions,
some
intermediates are formed, usually derivates of p-phenylenendiamine
mimicking
natural
melanin
granules.
(PPD), responsible
for dark
brown and
shades, or of
responsible
for blonde
During these
reactions,
someblack
intermediates
arep-aminophenol,
formed, usually
derivates
of
colors.
Some dyes contain(PPD),
also resorcinol,
but
it for
security reasons.
p-phenylenendiamine
responsible
formany
dark companies
brown and have
black eliminated
shades, or of
p-aminophenol,
colors.antibody
Some dyes
contain also
resorcinol,
but can
many
companies
PPD responsible
is an haptenfor
(anblonde
incomplete
stimulating
substance),
which
combine
with have
a protein
eliminated
it
for
security
reasons.
PPD
is
an
hapten
(an
incomplete
antibody
stimulating
substance),
molecule in the skin, leading to sensitization, which in future reapplication will lead to an allergic
which
can combine
with a protein
indifferent
the skin, severity
leading to
sensitization,
which inthe
future
reaction.
Allergic
skin reactions
to PPDmolecule
may have
and
sometime include
mucosae.
reapplication will lead to an allergic reaction. Allergic skin reactions to PPD may have different
For these reasons, a skin allergy test, made at least 48 hours before coloring, is mandatory before
severity and sometime include the mucosae. For these reasons, a skin allergy test, made at least 48
applying the coloring agent on the scalp in people with suspected PPD sensitization.
hours before coloring, is mandatory before applying the coloring agent on the scalp in people with
As
mentioned,
in dyes active ingredients are also present, like hydrogen peroxide, which bleaches
suspected
PPD sensitization.
out the original
color
oxidizing
molecules
thepresent,
dye, activate
the colorant
reactions,
As mentioned,and,
in dyes
active the
ingredients
are of
also
like hydrogen
peroxide,
which and
ammonia,
which
is
the
alkalizer.
Other
ingredients
are:
chelating
agents,
which
maintain
chemically
bleaches out the original color and, oxidizing the molecules of the dye, activate the colorant
stablereactions,
peroxideand
its activity,
deactivating
any catalytic
in the
product;
and
solvents,
which
and ammonia,
which
is the alkalizer.
Other metals
ingredients
are:
chelating
agents,
which
maintain
chemically
itsof
activity,
deactivating
anywhich
catalytic
metalsoil
in and
the product;
help to
improve
viscositystable
and peroxideand
solubilization
the dye;
surfactants,
remove
sebum from
andsurface.
solvents, which help to improve viscosity and solubilization of the dye; surfactants, which
the hair
remove
oilinterfere
and sebum
from
the dermoscopic
hair surface. diagnosis of hair diseases [10]: for example, permanent
Dyes can
with
some
Dyes can interfere with some dermoscopic diagnosis of hair diseases [10]: for example,
dye can penetrate hair follicle, giving a “black dot” appearance, distinctive for alopecia areata;
permanent dye can penetrate hair follicle, giving a “black dot” appearance, distinctive for alopecia
semipermanent dye can deposit on the scalp, mimicking sun exposure or excoriated lesions.
areata; semipermanent dye can deposit on the scalp, mimicking sun exposure or excoriated lesions.
Long-term
contact
of of
dyes
with
contact
dermatitis
which
can cause
a
Long-term
contact
dyes
withthe
thescalp
scalp can
can determine
determine a acontact
dermatitis
which
can cause
a
telogen
effluvium
(Figure
1),
but
in
severe
cases
can
induce
facial
edema.
telogen effluvium (Figure 1), but in severe cases can induce facial edema.
Figure 1. Contact dermatitis of the scalp due to permanent dye.
Figure 1. Contact dermatitis of the scalp due to permanent dye.
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3, 34
34
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2016, 3,
55 of
of 10
10
As mentioned, PPD is an extremely potent contact sensitizer, allowed at a concentration up of
mentioned,
PPD
is an extremely
contact
sensitizer,
allowed at a concentration
ofuse
6%
6% inAs
hair
dyes. Other
frequent
reportedpotent
hair dye
allergens
are toluene-2,5-diamine,
allowedupfor
in
hair
dyes.
Other
frequent
reported
hair
dye
allergens
are
toluene-2,5-diamine,
allowed
for
use
at
a
at a concentration up to 10%, p-aminophenol and m-aminophenol, the last at up to 2% [11].
concentration
up to
10%, p-aminophenol
m-aminophenol,
theand
lastselected
at up toderivatives
2% [11]. in hair dye
A study [11]
analyzed
chemically theand
actual
content of PPD
A study
[11] analyzed
chemically
the actual
content
of PPD
andspecifically,
selected derivatives
hair dye
products
causing
allergic contact
dermatitis
in nine
patients:
more
chemical in
analysis
of
products
causing
allergic
contact
dermatitis
in
nine
patients:
more
specifically,
chemical
analysis
the randomly collected products identified concentrations of the oxidative hair dyes similar to the
of the randomly
products
identified
concentrations
of the
oxidative
hair
dyesshows
similar
to
concentrations
in collected
the products
used by
the patients
with hair dye
dermatitis.
This
study
that
the concentrations
in the
used by the
with hairlower
dye dermatitis.
study shows
patients
can develop
hairproducts
dye dermatitis
frompatients
concentrations
than that This
permitted
in the
that patients
can (EU)
develop
hair dye
dermatitis from concentrations lower than that permitted in the
European
Union
Cosmetic
Directive.
European
Unioninteresting
(EU) Cosmetic
Directive.
In another
study
[12], authors provided a ranking concerning contact allergy risk,
In another
interesting
[12], authors
provided
ranking
allergy
analyzed
the predictions
forstudy
sensitization
potential
of 229ahair
dyes concerning
substances: contact
as result,
aboutrisk,
the
analyzed
sensitization
potential of 229 hair
dyes substances:
as result,
the
75%
of allthe
hairpredictions
dyes were for
predicted
to be strong/moderate
sensitizers,
even stronger
than about
PPD, and
75% ofofallthese
hair dyes
were
predicted
to be
sensitizers,
even
thanisPPD,
and
many
are not
currently
used
forstrong/moderate
diagnosing contact
allergy to
hairstronger
dyes. PPD
resulted
many potent
of thesethan
are not
currently used forwhile
diagnosing
contact
allergy
hairpotent
dyes. PPD
resulted
more
toluene-2,5-diamine,
resorcinol
seems
to betoless
than is
PPD.
Onlymore
22%
potent
toluene-2,5-diamine,
whileto
resorcinol
to beand
less 3%
potent
PPD. Only
of hair
of
hair than
dye substances
were predicted
be weak seems
sensitizers
werethan
predicted
to be22%
extremely
dye substances
were predicted to be weak sensitizers and 3% were predicted to be extremely weak
weak
or non-sensitizing.
or non-sensitizing.
More recently, Uter et al. [13] assembled complete information on the current practice of using
More recently,
Uteraetnew
al. [13]
assembled
complete information
on the current
practiceofofproven
using
hair cosmetics,
creating
European
hair cosmetics
series. They collected
all allergens
hair cosmetics,
newcontact
European
hair to
cosmetics
series. They
all allergens
of proven
importance
for creating
patients awith
allergy
hair cosmetics,
and collected
also allergens
with less
importance for
patients with
contact
allergy tothese
hair cosmetics,
also allergens
with less proven
importance,
underlining
the need
to evaluate
substances and
in specialized
departments,
and to
importance,
underlining the
need to evaluate these substances in specialized departments, and to
create
a cosmetovigilance
network.
create a cosmetovigilance network.
4.2. Bleaching Agents
4.2. Bleaching Agents
These products provide permanent hair lightening without the addition of a coloring tint,
These
products provide
permanent
hair lightening
without
the addition
of aThe
coloring
tint,requires
thanks
thanks
to substances
like hydrogen
peroxide,
ammonia
and persulfate
salts.
process
to substances
like hydrogen
peroxide,
ammonia
and
persulfate hydrogen
salts. The peroxide
process requires
time
and is realized
by a series
of color
stages. As
mentioned,
bleachestime
outand
the
is
realized
by
a
series
of
color
stages.
As
mentioned,
hydrogen
peroxide
bleaches
out
the
original
original color of the hair. The oxidizing agent, in alkaline solution, penetrates into the cortex of the
color after
of theraising
hair. The
agent,
in alkaline
solution, penetrates
intomelanin:
the cortex
the hair,
after
hair,
theoxidizing
scales of the
cuticle,
and chemically
modifies the
as of
result,
melanin
raising theare
scales
of the cuticle,
chemically
modifies
melanin:
result, melanin
granules
are
granules
dissolved,
leavingand
tiny
gaps in the
cortexthe
[7].
For thisas reasons,
repeated
bleaching
dissolved,
leaving
tiny
gaps
in
the
cortex
[7].
For
this
reasons,
repeated
bleaching
treatments
can
cause
treatments can cause an increased porosity of hair and permanently raised scales, leading to hair
an increased(Figure
porosity
weathering
2). of hair and permanently raised scales, leading to hair weathering (Figure 2).
(a)
(b)
Figure
2. (a)
(a) Hair
Hair weathering
weathering caused
caused by
repeated bleaching
bleaching treatment;
important hair
shaft
Figure 2.
by repeated
treatment; and
and (b)
(b) important
hair shaft
damage
of
hair
weathering,
clearly
visible
with
microscopic
examination.
damage of hair weathering, clearly visible with microscopic examination.
Persulfates can trigger immunomediate reactions, such as rhinitis, asthma, contact urticarial
Persulfates can trigger immunomediate reactions, such as rhinitis, asthma, contact urticarial and
and even anaphylaxis, but the exact immune mechanism is still unknown [14].
even anaphylaxis, but the exact immune mechanism is still unknown [14].
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5. Hair
HairStyles
Styles
5.1.
Permanent Waves
Waves
5.1. Permanent
The
of cosmetics
in lotions
or sprays
The topical
topical application
application of
cosmetics in
lotions or
sprays may
may give
give hair
hair aa temporary
temporary different
different
“style”
that
is
lost
after
the
first
shampooing.
A
modification
of
hair
internal
chemical
structure
“style” that is lost after the first shampooing. A modification of hair internal chemical structurewith
witha
specific
chemical
process
is
needed
to
change
in
a
permanent
way
the
shape
of
the
hair.
a specific chemical process is needed to change in a permanent way the shape of the hair.
A
permanent wave
is aa process
process that
that makes
makes curly
curly the
the hair,
hair, using
using chemicals
chemicals that
that break
break and
and reform
reform
A permanent
wave is
the
strong
disulfide
bonds
of
the
hair
shaft.
First
the
hair
is
washed
and
wrap
around
the
curler
the strong disulfide bonds of the hair shaft. First the hair is washed and wrap around the curler (the
(the
amplitude
amplitude of
of which
which will
will determinate
determinate the
the thickness
thickness of
of the
the curl),
curl), then
then waving
waving lotion
lotion in
in alkaline
alkaline base
base is
is
then
applied
(the
most
commonly
used
is
ammonium
thioglycolate):
it
raises
the
scales
of
the
cuticle
then applied (the most commonly used is ammonium thioglycolate): it raises the scales of the cuticle
and,
reaching inside
inside the
the cortex,
cortex, breaks
breaks the
the disulfide
disulfide bonds
bonds that
that give
give the
the natural
natural shape
shape of
of the
the hair.
hair.
and, reaching
After
After aa fixed
fixed time
time the
the waving
waving lotion
lotion is
is removed
removed with
with the
the rinse
rinse and
and aa neutralizer
neutralizer is
is applied,
applied, which
which
contains
oxidizing
agents,
like
hydrogen
peroxide,
that
rebuild
the
disulfide
bonds
in
a
different
order,
contains oxidizing agents, like hydrogen peroxide, that rebuild the disulfide bonds in a different
stabilizing
the
new
shape
of
the
hair.
Hair
waving
is
for
this
reason
the
most
dangerous
cosmetic
order, stabilizing the new shape of the hair. Hair waving is for this reason the most dangerous
procedures
for the hair
beshould
monitored
carefully. carefully.
cosmetic procedures
forand
theshould
hair and
be monitored
Trichorrhexis
nodosa
is
frequent
in
bleached
Trichorrhexis nodosa is frequent in bleached and
and permed
permed hair.
hair. The
The damage
damage to
to the
the cuticle
cuticle cells
cells
makes
makes them
them detach
detach and
and lead
lead to
to exposure
exposure to
to the
the hair
hair shaft
shaft cortex.
cortex. The
The hair
hair shaft
shaft shows
shows small
small whitish
whitish
knots
The hair
hair is
knots visible
visible with
with the
the unaided
unaided eye.
eye. The
is fragile
fragile and
and short
short due
due to
to breakage.
breakage. Microscopic
Microscopic
observation
of
the
hair
shaft
shows
one
or
more
knots
that
easily
break
off
producing
two
brush-like
observation of the hair shaft shows one or more knots that easily break off producing two brush-like
tips
tips (Figure
(Figure 3).
3).
Figure 3.
3. Multiple
hair shaft
shaft
Figure
Multiple Knots
Knots easily
easily break
break off,
off, producing
producing two
two brush-like
brush-like tips,
tips, are
are typical
typical hair
abnormalities
of
trichorrhexis
nodosa.
abnormalities of trichorrhexis nodosa.
5.2. Relaxers
5.2. Relaxers
The mechanisms of relaxing is the breaking of hair disulfide bonds, re-forming of hair shape
The mechanisms of relaxing is the breaking of hair disulfide bonds, re-forming of hair shape and
and re-making of the linkages. The shape of the hair changes from curly to straight. Multiple
re-making of the linkages. The shape of the hair changes from curly to straight. Multiple procedures
procedures or prolonged time of exposure to the relaxer may be needed to straighten tightly curled
or prolonged time of exposure to the relaxer may be needed to straighten tightly curled hair, such as
hair, such as that of African-Americans, producing hair weathering and breakage.
that of African-Americans, producing hair weathering and breakage.
5.3 Hair
5.3.
HairStraightening
Straightening
In the
the past,
consisted on
on applying
based oils
In
past, hair
hair straightener
straightener procedure
procedure consisted
applying petrolatum
petrolatum based
oils on
on the
the hair
hair
combined
with
hot
irons
or
hot
combs
pressed
to
the
hair,
but
the
effect
was
only
temporary.
combined with hot irons or hot combs pressed to the hair, but the effect was only temporary.
Nowadays, hair
hair straighteners
called chemical
relaxers, and
and the
the effect
effect of
of hair
hair straightening
straightening is
is
Nowadays,
straighteners are
are called
chemical relaxers,
permanent. Thanks
Thankstotothe
thehigh
high
(9.0–14.0),
solution
inflate
the opening
hair, opening
permanent.
pHpH
(9.0–14.0),
thethe
solution
inflate
the hair,
cuticlecuticle
scales, scales,
which
−) to penetrate into the hair fibers up to the endocuticle. The
which
allows
the
alkaline
agent
(OH
−
allows the alkaline agent (OH ) to penetrate into the hair fibers up to the endocuticle. The straightening
straightening product reacts with keratin, breaking and rearranging the disulfide bridges, which
making the spiral keratin molecule soft and stretched [5]. This procedure needs to be repeated every
12 weeks or longer.
Cosmetics 2016, 3, 34
7 of 10
product reacts with keratin, breaking and rearranging the disulfide bridges, which making the spiral
keratin molecule soft and stretched [5]. This procedure needs to be repeated every 12 weeks or longer.
Alkaline straighteners contain 1%–10% sodium hydroxide (lye-relaxer), lithium hydroxide,
calcium
hydroxide
or a combination of these ingredients such as guanidine carbonate and calcium
Cosmetics 2016,
3, 34
7 of 10
hydroxide (no-lye relaxers). Ammonium thioglycolate is another “no-lye” relaxers, which selectivity
weakens
the hair
cysteine bonds:
it is1%–10%
then oxidized
by hydroxide
hydrogen peroxide
and, lithium
applyinghydroxide,
a hot iron
Alkaline
straighteners
contain
sodium
(lye-relaxer),
during the
process,or
the
hair straightening
caningredients
be obtained.
Thyoglycolate
hydroxides
are not
calcium
hydroxide
a combination
of these
such
as guanidineand
carbonate
and calcium
mutagenic (no-lye
or carcinogenetic.
The main adverse
effects is
ofanother
hair straightening
are scalp
burns
and hair
hydroxide
relaxers). Ammonium
thioglycolate
“no-lye” relaxers,
which
selectivity
breakage.the
In particular,
in bonds:
the study
Shetty
et al., the
most common
adverse
reported
weakens
hair cysteine
it isofthen
oxidized
by hydrogen
peroxide
and,effects
applying
a hot after
iron
chemical
hair
straightening
frizzy haircan
in 67%,
dandruffThyoglycolate
in 61%, hair loss
47%, thinning
during
the
process,
the hairwere:
straightening
be obtained.
andinhydroxides
are and
not
weakening
of carcinogenetic.
hair in 40%, greying
of hair
in 22%,effects
and split
ends
in only 17% are
[15].scalp burns and hair
mutagenic or
The main
adverse
of hair
straightening
A keratin
treatmentincontaining
well-known
carcinogen
beenreported
performed
in
breakage.
In particular,
the study formaldehyde,
of Shetty et al., athe
most common
adversehas
effects
after
Brazil
with
success:
soon
the
health
vigilance
organizations
in
Brazil
(Agência
Nacional
de
Vigilância
chemical hair straightening were: frizzy hair in 67%, dandruff in 61%, hair loss in 47%, thinning and
Sanitária) prohibited
the use
of anyofproduct
containing
formaldehyde
concentrations
above 0.2%
weakening
of hair in 40%,
greying
hair in 22%,
and split
ends in onlyin17%
[15].
for cosmetics
Afterward,
the formaldehyde
was
replaced by a
potentially
more
mutagenic
and
A keratin[16].
treatment
containing
formaldehyde,
a well-known
carcinogen
has
been
performed
in
neurotoxic
which
belong to
the same aldehyde
group,
sold as aNacional
homemade
Brazil
withproduct,
success:glutaraldehyde,
soon the health
vigilance
organizations
in Brazil
(Agência
de
treatment. Sanitária)
The ingredients
used the
today
any
of these two
substances,in
but
are based on
Vigilância
prohibited
usedo
ofnot
anycontain
product
containing
formaldehyde
concentrations
formaldehyde-releasers
such
methylene the
glycol
or glyoxylicwas
acid.replaced
Acute contact
dermatitismore
may
above
0.2% for cosmetics
[16].asAfterward,
formaldehyde
by a potentially
occur as adverse
effect in previously
sensitized patients
[16].belong to the same aldehyde group, sold
mutagenic
and neurotoxic
product, glutaraldehyde,
which
as a homemade treatment. The ingredients used today do not contain any of these two substances,
6. Hair
Extensions
but
are based
on formaldehyde-releasers such as methylene glycol or glyoxylic acid. Acute contact
dermatitis
may occurhave
as adverse
effect
in previously
sensitized
patients
[16].as a beauty accessory for
Hair extensions
become
worldwide
increasingly
popular,
either
healthy people both as an aesthetic aid for patients with hair loss.
6. Hair
Extensions
They
are composed by synthetic or human hair, which can be attached to natural hair with various
techniques
like strand-by-strand,
weft or the
clip-in methods.
Theeither
cuticles
the extensions
must
Hair extensions
have becomethe
worldwide
increasingly
popular,
as of
a beauty
accessory
for
be
aligned
in
the
same
direction
of
the
natural
hair
and
they
are
usually
no
longer
than
twice
the
length
healthy people both as an aesthetic aid for patients with hair loss.
of theThey
person’s
natural hair
a cosmetically
harmonious
result.
are composed
byfor
synthetic
or human
hair, which
can be attached to natural hair with
Among
local side
effects,
we can mentionthe
traction
secondary
to the pulling
force applied
various
techniques
like
strand-by-strand,
weft alopecia,
or the clip-in
methods.
The cuticles
of the
to
the
hair
follicle
over
time
[17]
(Figure
4),
pruritus,
tenderness,
and
local
pain.
Hair
matting,
which
extensions must be aligned in the same direction of the natural hair and they are usually no longer
describes
reversible
or
irreversible
tangling
of
locks
of
hair
that
stick
together,
can
occur
[18]
(Figure
5).
than twice the length of the person’s natural hair for a cosmetically harmonious result.
Allergic contact
dermatitis
anaphylaxis
can arise
after secondary
sensitization
glues
or natural
Among
local side
effects, or
wecontact
can mention
traction
alopecia,
to to
the
pulling
force
rubber
latex
that
is
incorporated
into
the
adhesive
for
hair
extensions.
applied to the hair follicle over time [17] (Figure 4), pruritus, tenderness, and local pain. Hair matting,
Trichobezoars
formed by
consumption
of hair
extension
is athat
rare stick
causetogether,
of Rapunzel
which
describes reversible
or the
irreversible
tangling
of locks
of hair
can syndrome,
occur [18]
which
requires
surgery
and
psychiatric
examination
[19,20].
(Figure 5).
(a)
(b)
Figure
Small
alopecic
at of
the
site of of
attachment
of extension;
previous (b)
hairDermoscopic
extension;
Figure 4.4.(a)(a)
Small
alopecic
patch patch
at the site
attachment
previous hair
(b)
Dermoscopic
aspect
of
traction
alopecia:
multiple
broken
hairs
in
a
non
scarring
patch
of
alopecia.
aspect of traction alopecia: multiple broken hairs in a non scarring patch of alopecia.
Allergic contact dermatitis or contact anaphylaxis can arise after sensitization to glues or
natural rubber latex that is incorporated into the adhesive for hair extensions.
Trichobezoars formed by the consumption of hair extension is a rare cause of Rapunzel
syndrome, which requires surgery and psychiatric examination [19,20].
A case of homicidal strangulation by victim’s own artificial hair extensions has also been
described [21].
Cosmetics 2016, 3, 34
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Cosmetics 2016, 3, 34
8 of 10
Cosmetics 2016, 3, 34
8 of 10
Figure 5. Hair matting developed at the site of attachment of extensions.
Figure 5. Hair matting developed at the site of attachment of extensions.
7. Camouflage and Tattooing
A case of homicidal strangulation by victim’s own artificial hair extensions has also been
People
experiencing
undergo
emotional
distress
from their
condition, but fortunately
Figure 5. alopecia
Hair matting
developed
at the site
of attachment
of extensions.
described [21].
many new techniques have been developed to hide some hair disease.
7. Camouflage
Camouflage
and Tattooing
Tattooing
and
Patients affected
by alopecia areata can cover the scalp using many different styles of
hairpieces,
which
are
made
with human
oremotional
synthetic hair
fibers
tied
or woven
to abut
fabric
base. In
People experiencing alopecia
undergo
distress
from
their
condition,
fortunately
particular,
hairhave
wigsbeen
are the
most expensive,
and theydisease.
need to be washed and styled every
many new human
techniques
developed
to
to hide
hide some
some hair
hair disease.
two weeks,
lasting
2–3
years.
Synthetic
wigs
are
stronger
and
easier
to maintain. Types
of hairpieces,
hairpieces
Patients affected
alopecia
areata
can cover
the scalp
of
affectedbyby
alopecia
areata
can cover
the using
scalpmany
usingdifferent
many styles
different
styles of
include:
wig,
demiwig,
toupees,
fall,
cascade
and
wiglet
[22].
Allergic
contact
dermatitis
due to
which
are
made
with
human
or
synthetic
hair
fibers
tied
or
woven
to
a
fabric
base.
In
particular,
hairpieces, which are made with human or synthetic hair fibers tied or woven to a fabric base. In
incorporated
gluesare
or the
natural
rubber
latex car occur
(Figure
6). washed and styled every two weeks,
human
hairhuman
wigs
most
expensive,
they need
be
particular,
hair
wigs
are
the most and
expensive,
andtothey
need to be washed and styled every
lasting
2–3
years.
Synthetic
wigs
are
stronger
and
easier
to
maintain.
of hairpieces
include:
wig,
two weeks, lasting 2–3 years. Synthetic wigs are stronger and easier Types
to maintain.
Types of
hairpieces
demiwig,
toupees,
fall, cascade
andfall,
wiglet
[22]. Allergic
contact
due to incorporated
glues
include: wig,
demiwig,
toupees,
cascade
and wiglet
[22].dermatitis
Allergic contact
dermatitis due
to
or
natural rubber
latex
car occur
(Figure
6).car occur (Figure 6).
incorporated
glues
or natural
rubber
latex
Figure 6. Severe contact dermatitis of the scalp due to wig glue.
Pigmented hair and thickening fibers are effective to cover scalp alopecia in patients with
epidermolysis bullosa [23] or androgenetic alopecia [24].
Figure 6. Severe contact dermatitis of the scalp due to wig glue.
Severe
contactelectricity,
dermatitis so
of the
scalp due
to wigAglue.
They act bondingFigure
to the6.hair
by static
it appear
thicker.
fixative spray applied on
fibers can increase their stability. Pruritus and irritation and skin irritation can occur.
Pigmented hair and thickening fibers are effective to cover scalp alopecia in patients with
A
split or hair
flattened
hair direction
the parietal
whorl
can in
bepatients
cosmetically
Pigmented
and thickening
fibersaround
are effective
to cover
scalp(PW)
alopecia
with
epidermolysis bullosa [23] or androgenetic alopecia [24].
unpleasant.
A scalp
medical
technique
can[24].
camouflage this problem, using a jet black color
epidermolysis
bullosa
[23] ortattooing
androgenetic
alopecia
They act bonding to the hair by static electricity, so it appear thicker. A fixative spray applied on
ink ofThey
commercial
products,
high
satisfaction
of so
theitpatient
no complications
[25].
act bonding
to the with
hair by
static
electricity,
appear and
thicker.
A fixative spray
applied on
fibers can increase their stability. Pruritus and irritation and skin irritation can occur.
tattoo
technique,
called scalp
micropigmentation
has been
fibersAcan
increase
their stability.
Pruritus
and irritation and(SMP),
skin irritation
canrecently
occur. developed to
A split or flattened hair direction around the parietal whorl (PW) can be cosmetically
mimic
hair or
follicle
andhair
minimize
cosmetic
problem
derived
from can
hairbediseases.
It offers
good
A split
flattened
direction
around the
parietal
whorl (PW)
cosmetically
unpleasant.
unpleasant. A scalp medical tattooing technique can camouflage this problem, using a jet black color
solution
for patient
with technique
scarring alopecia,
alopeciathis
areata
or alopecia
chemotherapy
A
scalp medical
tattooing
can camouflage
problem,
using atotalis,
jet black
color ink of
ink of commercial products, with high satisfaction of the patient and no complications [25].
patients,
people
with scalp
deformities
and many
problems
[26].
commercial
products,
with high
satisfaction
of the other
patient
and no complications
[25].
A tattoo technique, called scalp micropigmentation (SMP), has been recently developed to
SMP is a permanent concealer, which use pigments of different hues in a variety of formulas
mimic hair follicle and minimize cosmetic problem derived from hair diseases. It offers good
and viscosities and instruments employing needles in various sizes and shapes. Many factors have
solution for patient with scarring alopecia, alopecia areata or alopecia totalis, chemotherapy
patients, people with scalp deformities and many other problems [26].
SMP is a permanent concealer, which use pigments of different hues in a variety of formulas
Cosmetics 2016, 3, 34
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A tattoo technique, called scalp micropigmentation (SMP), has been recently developed to mimic
hair follicle and minimize cosmetic problem derived from hair diseases. It offers good solution for
patient with scarring alopecia, alopecia areata or alopecia totalis, chemotherapy patients, people with
scalp deformities and many other problems [26].
SMP is a permanent concealer, which use pigments of different hues in a variety of formulas and
viscosities and instruments employing needles in various sizes and shapes. Many factors have to be
evaluated when performing this technique, like aesthetic factors, presence of scars on the scalp, skin
color, hair color, the amount of remaining hair, and the color and viscosity of the pigments used.
The SMP process begins by inserting a micro droplet of pigment through the skin and into the
upper dermis, using a standard tattoo instrument, which supports between one and six needles cycling
between 100 and 150 cycles per second. Multiple sessions are needed to complete the procedure.
The operator makes technical and artistic judgments as the process advances, millimeter by
millimeter, customizing each treatment on the patient.
Risks and complications include infection, allergies to the components in the pigments and
magnetic resonance imaging complications, such as swelling and pain from the metals in the pigments.
Little is known about the chemical composition, adsorption, distribution, metabolism, and
excretion of inks, and other studies are needed to learn more about this procedure.
8. Conclusions
Hair styling play a very important role in people’s physical aspect and self-perception. Hair
cosmetics is a very interesting evolving field, and hair industry is costantly investing resources to find
new components, molecules and hair procedures. Usually patients with hair disorders are the main
actors targeted to these products, but in daily life all people care of hair beauty and health.
Dermatologists should always be update on new formulations, hair technique or adverse
effects of hair products designed to beautify and modify the hair, in order to better treat hair and
scalp contiditions.
Author Contributions: The Authors contribute equally to this work.
Conflicts of Interest: The authors declare no conflict of interest.
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