Phenylephrine / Promethazine Side Effects

Medically reviewed by Drugs.com. Last updated on Oct 19, 2023.

Applies to phenylephrine / promethazine: oral syrup.

Important warnings This medicine can cause some serious health issues

Do not give this medicine to a child younger than 2 years old. Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

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

A dangerous drug interaction could occur.

MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

Get emergency medical help if you have any of these signs of an allergic reaction while taking phenylephrine/promethazine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

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

• seizure (convulsions);

• weak or shallow breathing;

• jaundice (yellowing of the skin or eyes);

• confusion, hallucinations;

• sudden weakness or ill feeling, fever, chills, sore throat, mouth sores, red or swollen gums, trouble swallowing;

• uncontrollable movements of your eyes, lips, tongue, face, arms, or legs; or

• severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Common side effects may include:

• dizziness, drowsiness;

• dry mouth, nose, or throat;

• blurred vision; or

• constipation.

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 phenylephrine / promethazine: oral syrup.

General adverse events

One of the most commonly reported adverse reactions has included drowsiness.^[Ref]

Nervous system

Promethazine:

• Frequency not reported: Sedation, sleepiness, somnolence, dizziness, tremor, weakness, and extrapyramidal symptoms such as oculogyric crisis, torticollis, and tongue protrusion, incoordination, seizures, neuroleptic malignant syndrome

Phenylephrine:

• Frequency not reported: Dizziness, tremor, weakness^[Ref]

Psychiatric

Promethazine:

• Frequency not reported: Euphoria, confusion, disorientation, restlessness, anxiety, nervousness, excitation, catatonic-like states, hysteria, hallucinations, nightmares, insomnia, delirium, agitated behavior

Phenylephrine:

• Frequency not reported: Restlessness, anxiety, nervousness

Cardiovascular

Promethazine:

• Frequency not reported: Increased or decreased blood pressure, tachycardia, bradycardia, faintness

Phenylephrine:

• Frequency not reported: Hypertension^[Ref]

Ocular

Promethazine:

• Frequency not reported: Blurred vision, diplopia^[Ref]

Gastrointestinal

Promethazine:

• Frequency not reported: Dry mouth, nausea, vomiting^[Ref]

Hematologic

Promethazine:

• Frequency not reported: Leukopenia, thrombocytopenia, thrombocytopenic purpura, agranulocytosis^[Ref]

Dermatologic

Promethazine:

• Frequency not reported: Dermatitis, photosensitivity, urticaria, angioneurotic edema^[Ref]

Respiratory

Promethazine:

• Frequency not reported: Respiratory distress, asthma, nasal stuffiness, apnea

Phenylephrine:

• Frequency not reported: Respiratory distress^[Ref]

Hepatic

Promethazine:

• Frequency not reported: Jaundice

Other

Promethazine:

• Frequency not reported: Lassitude, tinnitus, fatigue

Phenylephrine:

• Frequency not reported: Precordial pain

Further information

Phenylephrine/promethazine 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.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer