Excedrin PM Side Effects

Generic name: acetaminophen / diphenhydramine

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

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

Applies to acetaminophen / diphenhydramine: oral liquid, oral tablet.

Important warnings This medicine can cause some serious health issues

Use this medicine exactly as directed.

An overdose of acetaminophen can damage your liver or cause death.

Taking too much diphenhydramine can lead to serious heart problems, seizures, coma, or death.

Do not use this medicine to make a child sleepy.

This medicine is not for use in anyone younger than 12 years old.

Ask a doctor or pharmacist before using any other medicine that may contain acetaminophen or diphenhydramine.

Taking too much of either medicine can lead to a fatal overdose.

Drinking alcohol may increase your risk of liver damage while taking acetaminophen.

Stop taking this medicine and call your doctor right away if you have skin redness or a rash that spreads and causes blistering and peeling.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

In rare cases, acetaminophen may cause a severe skin reaction that can be fatal. This could occur even if you have taken acetaminophen in the past and had no reaction. Stop taking this medicine and call your doctor right away if you have skin redness or a rash that spreads and causes blistering and peeling. If you have this type of reaction, you should never again take any medicine that contains acetaminophen.

Stop using the medicine and call your doctor at once if you have:

• severe drowsiness;

• painful or difficult urination; or

• liver problems--loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

• drowsiness;

• constipation;

• decreased urination;

• dry eyes, blurred vision; or

• dry mouth, nose, or throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For healthcare professionals

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

General adverse events

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

Hepatic

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]

Hypersensitivity

Acetaminophen (paracetamol):

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

Diphenhydramine:

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

Nervous system

Acetaminophen (paracetamol)-diphenhydramine:

• Frequency not reported: Dizziness, difficulty concentrating, unsteadiness

Diphenhydramine:

• 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]

Psychiatric

Acetaminophen (paracetamol)-diphenhydramine:

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

Cardiovascular

Acetaminophen (paracetamol):

• Frequency not reported: Hypotension

Diphenhydramine:

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

Gastrointestinal

Acetaminophen (paracetamol):

• Rare (less than 0.1%): Acute pancreatitis

Diphenhydramine:

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

Renal

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]

Hematologic

Acetaminophen (paracetamol):

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

Diphenhydramine:

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

Dermatologic

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]

Ocular

Diphenhydramine:

• Frequency not reported: Blurred vision^[Ref]

Genitourinary

Diphenhydramine:

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

Respiratory

Acetaminophen (paracetamol):

• Rare (less than 0.1%): Eosinophilic pneumonia
• Postmarketing reports: Bronchospasm

Diphenhydramine:

• Frequency not reported: Thickening of bronchial secretions^[Ref]

Musculoskeletal

Diphenhydramine:

• Frequency not reported: Twitching or jerking muscles^[Ref]

Further information

Excedrin PM 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.

Medical Disclaimer