Acetaminophen / Dextromethorphan / Phenylephrine Side Effects

Medically reviewed by Drugs.com. Last updated on Apr 16, 2024.

Applies to acetaminophen / dextromethorphan / phenylephrine: oral capsule, oral powder for reconstitution, oral syrup, oral tablet.

Important warnings This medicine can cause some serious health issues

Do not use this medicine if you have taken an MAO inhibitor in the past 14 days.

A dangerous drug interaction could occur.

MAO inhibitors include isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, and tranylcypromine.

Do not take more of this medication than is recommended. An overdose of acetaminophen can damage your liver or cause death. Call your doctor at once if you have nausea, pain in your upper stomach, itching, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of your skin or eyes).

In rare cases, acetaminophen may cause a severe skin 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.

Get emergency medical help if you have any of these signs of an allergic reaction while taking acetaminophen/dextromethorphan/phenylephrine: hives; difficulty 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 acetaminophen, dextromethorphan, and phenylephrine and call your doctor at once if you have:

• chest pain, fast, slow, or uneven heart rate;

• severe dizziness, feeling like you might pass out;

• mood changes, confusion, hallucinations, seizure (convulsions);

• little or no urinating;

• nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

• dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, chest pain, uneven heartbeats, seizure).

Common side effects may include:

• dizziness, weakness, mild headache;

• diarrhea, upset stomach;

• dry mouth, nose, or throat;

• feeling nervous, restless, irritable, or anxious; or

• sleep problems (insomnia).

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/dextromethorphan/phenylephrine: oral capsule, oral liquid, oral powder for reconstitution, oral suspension, oral syrup, oral tablet.

Hepatic

• Very rare (less than 0.01%): Hepatic dysfunction (acetaminophen)^[Ref]

Nervous system

• Uncommon (0.1% to 1%): Drowsiness, dizziness, fatigue, dystonias (dextromethorphan)
• Frequency not reported: Headache, dizziness, insomnia (phenylephrine)
• Postmarketing reports: Serotonin syndrome (dextromethorphan)^[Ref]

Serotonin syndrome has been reported with concomitant use of dextromethorphan and either a monoamine oxidase inhibitor (MAOI) or a serotonergic drug such as a selective serotonin reuptake inhibitor (SSRI). Serotonin syndrome causes changes in mental status, restlessness, myoclonus, hyperreflexia, diaphoresis, shivering, tremor, and hypertension.^[Ref]

Hypersensitivity

• Rare (less than 0.1%): Allergic reactions (e.g. rash, urticaria, allergic dermatitis) (phenylephrine)
• Very rare (less than 0.01%): Anaphylaxis, cutaneous hypersensitivity reactions (including skin rashes, angioedema, and Stevens Johnson syndrome) (acetaminophen)
• Postmarketing reports: Allergic reactions (e.g. rash, urticaria, angioedema) (dextromethorphan)^[Ref]

Cardiovascular

• Rare (less than 0.1%): Tachycardia, palpitations (phenylephrine)
• Frequency not reported: Increased blood pressure, arrhythmias (phenylephrine)^[Ref]

Gastrointestinal

• Uncommon (0.1% to 1%): Gastrointestinal disturbance, nausea, vomiting, abdominal discomfort, constipation (dextromethorphan)
• Frequency not reported: Nausea, vomiting (phenylephrine)^[Ref]

Psychiatric

• Frequency not reported: Nervousness, anxiety (phenylephrine)^[Ref]

Respiratory

• Very rare (less than 0.01%): Bronchospasm (especially in patients sensitive to aspirin/other NSAIDs) (acetaminophen)^[Ref]

Genitourinary

• Rare (less than 0.1%): Dysuria, urinary retention (phenylephrine)^[Ref]

Dysuria and urinary retention are most likely to occur with preexisting bladder outlet obstruction (e.g. prostatic hypertrophy)^[Ref]

Hematologic

• Very rare (less than 0.01%): Thrombocytopenia (acetaminophen)^[Ref]

Ocular

• Rare (less than 0.1%): Mydriasis, acute closure glaucoma (phenylephrine)^[Ref]

Phenylephrine is most likely to cause mydriasis and acute closure glaucoma in patients with pre-existing closed angle glaucoma.^[Ref]

Further information

Acetaminophen/dextromethorphan/phenylephrine 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