acetaminophen, Tylenol and Others (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

SIDE EFFECTS: When used appropriately, side effects with acetaminophen are not common. The most serious side effect is liver damage due to large doses, chronic use or concomitant use with alcohol or other drugs that also damage the liver.

Chronic alcohol use may also increase the risk of stomach bleeding.

Other important side effects include:

  • hypersensitivity reactions and
  • serious skin reactions

WARNING: Acetaminophen can cause liver failure which can lead to liver transplant and possibly death. Liver toxicity is more commonly due to high amounts of acetaminophen dose, especially when there is more than one product containing acetaminophen.



PREPARATIONS: Solution/suspension: 160 mg/5 ml; Liquid: 500 mg/ml; Chewable tablets: 80, 160 mg; Tablet (disintegrating): 80, 160 mg; Caplets: 325, 500, 650 mg; Caplet (extended release): 650 mg; Gelcaps: 500 mg; Geltabs: 500 mg

STORAGE: Tablets and solutions should be stored at room temperature 15 C to 30 C (59 F to 86 F). Suppositories should be refrigerated below 27 C (80 F).


  • The dose for adults is 325 to 650 mg every 4 hours or 500 mg every 8 hours when using immediate release formulations.
  • The dose for extended release caplet is 1300 mg every 8 hours.
  • The maximum daily dose is 4 grams.
  • The oral dose for a child is based on the child's age and weight.
  • If less than 12 years old the dosing is 10-15 mg/kg every 6-8 hours not to exceed 2.6 g/day (5 doses).
  • If older than 12 years of age the dose is 40-60 mg/kg/day every 6 hours not to exceed 3.75 g/day (5 doses).

DRUG INTERACTIONS: Acetaminophen is metabolized (eliminated by conversion to other chemicals) by the liver. Therefore drugs that increase the action of liver enzymes that metabolize acetaminophen, for example, carbamazepine (Tegretol), isoniazid, rifampin (Rifamate, Rifadin, and Rimactane), reduce the levels of acetaminophen and may decrease the effectiveness of acetaminophen. Doses of acetaminophen greater than the recommended doses are toxic to the liver and may result in severe liver damage. The potential for acetaminophen to harm the liver is increased when it is combined with alcohol or drugs that also harm the liver.

Cholestyramine (Questran) reduces the effect of acetaminophen by decreasing its absorption into the body from the intestine. Therefore, acetaminophen should be administered 3 to 4 hours after cholestyramine or one hour before cholestyramine.

Medically Reviewed by a Doctor on 12/26/2014

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