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Anacin PM Aspirin Free Side Effects

Generic name: acetaminophen / diphenhydramine

Medically reviewed by Last updated on Apr 23, 2024.

Note: This document contains side effect information about acetaminophen / diphenhydramine. Some dosage forms listed on this page may not apply to the brand name Anacin PM Aspirin Free.

Applies to acetaminophen / diphenhydramine: oral tablet.

Serious side effects

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Other side effects

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

For Healthcare Professionals

Applies to acetaminophen/diphenhydramine: oral capsule, oral liquid, oral powder for reconstitution, oral tablet.


The most commonly reported adverse reactions which are also related to use are drowsiness or sleepiness.[Ref]


Acetaminophen (paracetamol):

Frequency not reported: Severe and sometimes fatal dose-dependent hepatitis in alcoholic patients; hepatotoxicity from chronic acetaminophen therapy at therapeutic doses has occurred despite a lack of risk factors for toxicity

Postmarketing reports: Hepatic dysfunction[Ref]

Alcoholic patients may develop hepatotoxicity after even modest doses of acetaminophen. In healthy patients, approximately 15 grams of acetaminophen is necessary to deplete liver glutathione stores by 70% in a 70 kg person. However, hepatotoxicity has been reported following smaller doses. Glutathione concentrations may be repleted by the antidote N-acetylcysteine. One case report has suggested that hypothermia may also be beneficial in decreasing liver damage during overdose.

In a recent retrospective study of 306 patients admitted for acetaminophen overdose, 6.9% had severe liver injury but all recovered. None of the 306 patients died.[Ref]


Acetaminophen (paracetamol):

Rare (less than 0.1%): Hypersensitivity including anaphylaxis and fixed drug eruptions


Frequency not reported: Rash, pruritus, eczema, photosensitivity, urticaria, dyspnea, angioedema[Ref]

Nervous system

Acetaminophen (paracetamol)-diphenhydramine:

Frequency not reported: Dizziness, difficulty concentrating, unsteadiness


Very common (10% or more): Drowsiness, sedation, convulsions, headache, paraesthesia, dyskinesias, toxic encephalopathy, delirium[Ref]

The CNS depressant effect of diphenhydramine parallels its plasma concentrations. The plasma concentration threshold for sedation is 30 to 42 ng/mL, and to cause mental impairment is 58 to 74 ng/mL.

Dystonic reactions have been accompanied by dizziness, mental confusion, rigidity, lip and tongue protrusion, trismus, torticollis, and swallowing difficulties and generally resolve spontaneously. Toxic encephalopathy has been reported in a child with chicken pox treated generously with topical diphenhydramine.

Delirium has been reported in elderly patients with mild dementia following a small oral dose of diphenhydramine.[Ref]


Acetaminophen (paracetamol)-diphenhydramine:

Frequency not reported: Irritability, nervousness, anxiety, hallucinations, paradoxical excitation[Ref]


Acetaminophen (paracetamol):

Frequency not reported: Hypotension


Frequency not reported: Hypotension, tachycardia, palpitations[Ref]


Acetaminophen (paracetamol):

Rare (less than 0.1%): Acute pancreatitis


Frequency not reported: Nausea, dry mouth, dyspepsia, constipation[Ref]


Acetaminophen (paracetamol):

Rare (less than 0.1%): Acute tubular necrosis, interstitial nephritis[Ref]

Acute tubular necrosis usually occurs in conjunction with liver failure, but has been observed as an isolated finding in rare cases.[Ref]


Acetaminophen (paracetamol):

Rare (less than 0.1%): Thrombocytopenia, methemoglobinemia (with resulting cyanosis in the setting of acute overdose)


Rare (less than 0.1%): Hemolytic anemia, thrombocytopenia, agranulocytosis[Ref]


Acetaminophen (paracetamol):

Rare (less than 0.1%): Serious skin reactions including erythematous skin rashes, bullous erythema and purpura fulminans, Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP)[Ref]



Frequency not reported: Blurred vision[Ref]



Frequency not reported: Urinary retention, dysuria, urinary difficulty[Ref]


Acetaminophen (paracetamol):

Rare (less than 0.1%): Eosinophilic pneumonia

Postmarketing reports: Bronchospasm


Frequency not reported: Thickening of bronchial secretions[Ref]



Frequency not reported: Twitching or jerking muscles[Ref]

More about Anacin PM Aspirin Free (acetaminophen / diphenhydramine)

Patient resources

Other brands

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Other formulations

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1. (2005) "Product Information. Tylenol Extra Strength PM (acetaminophen-diphenhydramine)." Johnson and Johnson/Merck

2. Lee WM (1995) "Medical progress: drug-induced hepatotoxicity." N Engl J Med, 333, p. 1118-27

3. Brown G (1996) "Acetaminophen-induced hypotension." Heart Lung, 25, p. 137-40

4. Gursoy M, Haznedaroglu IC, Celik I, Sayinalp N, Ozcebe OI, Dundar SV (1996) "Agranulocytosis, plasmacytosis, and thrombocytosis followed by a leukemoid reaction due to acute acetaminophen toxicity." Ann Pharmacother, 30, p. 762-5

5. Kawada A, Hiruma M, Noguchi H, Ishibashi A (1996) "Fixed drug eruption induced by acetaminophen in a 12-year-old girl." Int J Dermatol, 35, p. 148-9

6. Barranco P, LopezSerrano MC, MorenoAncillo A (1998) "Anaphylactic reaction due to diphenhydramine." Allergy, 53, p. 814

7. Halevi A, BenAmitai D, Garty BZ (2000) "Toxic epidermal necrolysis associated with acetaminophen ingestion." Ann Pharmacother, 34, p. 32-4

8. Sexton JD, Pronchik DJ (1997) "Diphenhydramine induced psychosis with therapeutic doses." Am J Emerg Med, 15, p. 548-9

9. Richardson GS, Roehrs TA, Rosenthal L, Koshorek G, Roth T (2002) "Tolerance to daytime sedative effects of h1 antihistamines." J Clin Psychopharmacol, 22, p. 511-5

10. Eguia L, Materson BJ (1997) "Acetaminophen-related acute renal failure without fulminant liver failure." Pharmacotherapy, 17, p. 363-70

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.