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Terfenadine Side Effects

Applies to terfenadine: oral tablet.


Terfenadine was withdrawn from the U.S. market in 1998.

Do not take terfenadine with any of the following medicines: the antifungal drugs ketoconazole (Nizoral) or itraconazole (Sporanox); the antibiotics erythromycin (E.E.S., E-Mycin, Ery-Tab), clarithromycin (Biaxin), or azithromycin (Zithromax); or the ulcer drug cimetidine (Tagamet, Tagamet HB). A dangerous drug interaction could occur.

If you experience any of the following serious side effects, stop taking terfenadine and call your doctor immediately or seek emergency medical attention.

If you experience any of the following less serious side effects, continue taking terfenadine and talk to your doctor:

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

For Healthcare Professionals

Applies to terfenadine: oral tablet.


Terfenadine use may cause prolongation of the QT interval. Most cardiovascular events related to terfenadine occur in patients taking more than the recommended dose of 60 mg twice a day, in patients with higher-than-normal terfenadine serum concentrations, and in patients who are at risk for cardiac events. Patients with liver disease are also at risk of cardiovascular toxicity due to potential accumulation of the drug. Other predisposing factors for cardiovascular toxicity include congenital forms of QT interval prolongation, coronary artery disease, and electrolyte disorders including hypokalemia and hypomagnesemia. Although rare, arrhythmias have been reported in patients on recommended doses without apparent risk factors.[Ref]

Cardiovascular toxicity has been associated with the use of terfenadine. Reported effects include dizziness, syncopal episodes, palpitations, ventricular arrhythmias (including torsades de pointes), cardiac arrest, and cardiac death.[Ref]

Nervous system

Headaches have been reported in approximately 6% of treated patients. Terfenadine has not been demonstrated to cause significant drowsiness, sedation, or impaired psychomotor skills.[Ref]


Gastrointestinal effects of terfenadine are rare and include nausea and dry mouth.[Ref]


A study of the effects of terfenadine on the urination of eight healthy male volunteers and 11 males with benign prostatic hypertrophy was not able to confirm a consistent effect on voiding characteristics.[Ref]

Urinary retention has been reported rarely.[Ref]


Acute hepatitis, cholestatic hepatitis, and jaundice have been reported rarely in patients taking terfenadine. Hepatic dysfunction has been reversible upon discontinuation of the drug.[Ref]

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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.