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Unisom PM Pain Side Effects

Generic name: acetaminophen / diphenhydramine

Medically reviewed by Drugs.com. Last updated on Feb 3, 2024.

Note: This document provides detailed information about Unisom PM Pain Side Effects associated with acetaminophen / diphenhydramine. Some dosage forms listed on this page may not apply specifically to the brand name Unisom PM Pain.

Applies to acetaminophen / diphenhydramine: oral tablet.

Serious side effects of Unisom PM Pain

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 of Unisom PM Pain

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 https://www.fda.gov/medwatch.

For healthcare professionals

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

General

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

Hepatic

Acetaminophen (paracetamol):

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]

Hypersensitivity

Acetaminophen (paracetamol):

Diphenhydramine:

Nervous system

Acetaminophen (paracetamol)-diphenhydramine:

Diphenhydramine:

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]

Psychiatric

Acetaminophen (paracetamol)-diphenhydramine:

Cardiovascular

Acetaminophen (paracetamol):

Diphenhydramine:

Gastrointestinal

Acetaminophen (paracetamol):

Diphenhydramine:

Renal

Acetaminophen (paracetamol):

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

Hematologic

Acetaminophen (paracetamol):

Diphenhydramine:

Dermatologic

Acetaminophen (paracetamol):

Ocular

Diphenhydramine:

Genitourinary

Diphenhydramine:

Respiratory

Acetaminophen (paracetamol):

Diphenhydramine:

Musculoskeletal

Diphenhydramine:

References

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

Unisom PM Pain side effects can vary depending on the individual. 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.