Terfenadine Side Effects

It is possible that some side effects of terfenadine may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to terfenadine: oral tablet

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

  • an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);

  • an irregular heartbeat; or

  • seizures.

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

  • drowsiness or dizziness;

  • headache;

  • nervousness;

  • nausea, diarrhea, or abdominal discomfort;

  • dry mouth; or

  • dry skin or itchiness.

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.

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.

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.


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


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.

Urinary retention has been reported rarely.


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

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.