ACETAMINOPHEN
Information That Patients Need to Know About Their Medication
Kasey Malotte, PharmD
Pain and Palliative Care Pharmacy Resident
University of Maryland, School of Pharmacy
Baltimore, Maryland
Mary Lynn McPherson, PharmD, MA, BCPS, CPE
Professor and Vice Chair
Department of Pharmacy Practice and Science
University of Maryland, School of Pharmacy
Baltimore, Maryland
What is acetaminophen?
How do I take this medication?
Acetaminophen is a medication that is readily available
over-the-counter (which means you can buy it without a
prescription) in many different dosage forms as seen in
the table below. It can be used in patients of all ages and
with varying underlying medical conditions. Other names
that you may recognize are Tylenol, Excedrin, and Feverall.
Sometimes acetaminophen is just one of the medications
in a combination medication such as Percocet, Vicodin,
Nyquil, Coricidin, Midol, and others!
Ask your pharmacist and follow instructions shown on the
product packaging or prescription bottle. For adults, acetaminophen can be taken 4 to 6 times throughout the day as
long as the total amount taken is not more than 3,000 mg
for the whole day. Under the supervision of a prescriber, up
to 4,000 mg a day of acetaminophen can be taken.
Acetaminophen is dosed by weight for children—ask the
pharmacist or doctor for dosing assistance. For an infant or
a child less than 2 years old, acetaminophen cannot be used
without instruction from a prescriber.
Do not take higher than recommended doses, extra doses,
or take it longer than recommended. Carefully check the
labels of other medications you are taking to make sure they
do not also contain acetaminophen. Your pharmacist can
help you with this as well.
Acetaminophen can be taken with food or on an empty
stomach (but always with a full glass of water). Sometimes
taking with food can lessen any upset stomach that may occur.
If you are taking the oral solution or suspension, or giving
a dose to a child, use a calibrated measuring spoon instead
of a household teaspoon to measure the dose.
Table. Acetaminophen
Dosage Formulation
Strength(s)
Tablet
325, 500 mg
Tablet, dispersible
80, 160 mg
Tablet, chewable
80 mg
Tablet, extended-release
650 mg
Capsule
500 mg
Oral Solution
80 mg/0.8 ml, 100 mg/ml,
160 mg/5 ml, 325 mg/5 ml,
500 mg/15 ml, 1000 mg/30 ml
Oral Suspension
80 mg/0.8 ml, 160 mg/5 ml
Oral Gel
160 mg/5 ml
Rectal Suppository
80, 120, 325, 650 mg
Intravenous
10 mg/ml
What is it used for?
It is commonly used to reduce a fever and to treat both
acute pain (such as headache, toothache, sprains or muscle strains) and chronic pain (back pain and osteoarthritis).
Acetaminophen may be purchased over-the-counter (without a prescription).
Is this drug safe?
Based on current research, doses up to 3,000 mg per day,
or 4,000 mg per day under a doctor’s supervision, are considered safe. However, taking more than 4,000 mg per day
may cause liver damage, either as one large dose, or excessive doses over weeks or months. If you already have liver
problems, acetaminophen may not be the right drug for you.
It can be taken with most medications, foods, and drinks.
Do not take acetaminophen if you have a history of alcohol
abuse, or consume alcohol while using acetaminophen. You
should also avoid acetaminophen if you have a history of
liver disease (including hepatitis), severe kidney disease, or
phenylketonuria. If you are taking a blood thinner such as
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Acetaminophen
warfarin you should talk with your prescriber before starting this medication.
How do I know if it is working?
If taking this medication for pain or to lower a fever, then
you should feel better! It usually takes about 45 minutes for
oral, liquid, or tablet acetaminophen to start working. The
oral disintegrating tablets start to work in about 20 minutes.
Rectal suppositories can take a little longer to start working—
up to 2 hours. Acetaminophen usually lasts about 4 hours for
pain relief and fever reduction, so you shouldn’t take it more
often. If your pain does not get better or your fever does not
start to come down after 1 to 2 hours, you may want to call
your pharmacist or prescriber to see if you need a larger dose
or if a different medication may be right for you.
How do I know if something is wrong?
You should contact your prescriber if you have any swelling, rash, or trouble breathing. If you become nauseated,
try taking acetaminophen with food or milk.
How do I store my medication?
Store in a cool, dry place, such as your nightstand. Don’t
store acetaminophen or any medications in a humid place
such as the kitchen or bathroom. All medications should be
stored in a location in your house that is out of reach from
pets, children, or adults who could accidently take or misuse this medication.
What do I do if I miss a dose?
If you are taking acetaminophen on a regular schedule take it as
soon as you remember. However do not take another dose until
the appropriate time has passed (such as 4 hours for a regular
tablet or capsule). If you are unsure what to do, contact your
pharmacist. Importantly, you should never take double the recommended dose. If you are taking acetaminophen occasionally
for pain or fever, then you can just take the medication when
you need it, but no sooner than directed on the box.
References
1. Tylenol [package label] 325mg acetaminophen tablet. Fort Washington, PA:
McNeil-PPC, Inc; 2013. NDC 55154-1918-0.
2. Acetaminophen Preparations. Pediatric & Neonatal Lexi-Drugs. Hudson, Oh:
Lexicomp, Inc; 2014.
3. Guggenheimer J, Moore PA. The therapeutic applications of and risks associated with acetaminophen use: a review and update. JADA. 2011;142:38-44.
4. The Acetaminophen Hepatotoxicity Working Group. Recommendations for FDA
Interventions to Decrease the Occurrence of Acetaminophen Hepatotoxicity.
http://www.fda.gov/downloads/UCM164898.pdf. Accessed January 30, 2015.
5. Food and Drug Administration, HHS. Organ-specific warnings; internal analgesic, antipyretic, and antirheumatic drug products for over-the-counter human
use; final monograph. Final rule. Fed Regist. 2009;74(81):19385-19409.
6. Sharma CV, Mehta V. Paracetamol: mechanisms and updates. Contin Educ
Anaesth Crit Care Pain. 2014;14(4):153-158.
7. Whaba H. The antipyretic effect of ibuprofen and acetaminophen in children.
Pharmacotherapy. 2004;24(2):280-284.
8. Moller PL, Norholt SE, Ganry HE, et al. Time to onset of analgesia and
analgesic efficacy of effervescent aceta-minophen 1000 mg compared to
tablet acetaminophen 1000 mg in postoperative dental pain: a single-dose,
dou-ble-blind, randomized, placebo-controlled study. J Clin Pharmacol.
2000;40(4):370-378.
Prescriber Quick Fact Card
Name:
Indications:
Acetaminophen (Tylenol, Excedrin, etc)
Pain or fever
Class:
Directions for Use:
Anti-pyretic, analgesic
Every 4-6 hrs either scheduled or as needed
MAX 3-4 g/d for adults
Dosage Forms:
•Tablet (325 mg, 500 mg)
•Dispersible tablet (80 mg, 160 mg)
•Chewable tablet (80 mg)
•Extended-release tablet (650 mg)
•Capsule/Gelcap/Geltab (500 mg)
•Injection (10 mg/ml - 100 ml vial)
•Oral Solution (80 mg/0.8 ml, 100 mg/ml, 160 mg/5 ml,
325 mg/5 ml, 500 mg/15 ml, 1000 mg/30 ml)
•Oral Gel (160 mg/5 ml)
•Rectal Suppository (80 mg, 120 mg, 325 mg, 650 mg)
Cautions:
Do not use with alcohol, may diminish effectiveness of
vaccines, caution in liver impairment
Side Effects:
Well-tolerated, increased LFTs,* hepatotoxicity*, rash*
Monitoring:
Relief of symptoms, assess alcohol use and signs/symptoms
of liver disease
* rare but serious side effects
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