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What is the most important information I should know about terfenadine?

Terfenadine was withdrawn from the U.S. market in 1998.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

What is terfenadine?

Terfenadine was withdrawn from the U.S. market in 1998.

Terfenadine is an antihistamine. Antihistamines prevent sneezing, runny nose, itching and watering of the eyes, and other allergic symptoms.

Terfenadine is used to treat allergies, hives (urticaria), and other allergic inflammatory conditions.

Terfenadine may also be used for purposes other than those listed in this medication guide.

Who should not take terfenadine?

You cannot take terfenadine if you are taking 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 side effect involving irregular heartbeats could occur if you take terfenadine with any of the medicines listed above.

Before taking this medication, tell your doctor if you have

• asthma or another lung disease;

• low potassium levels in your blood;

• urinary retention or an enlarged prostate;

• kidney or liver disease; or

• heart disease, especially an irregular heartbeat.

You may not be able to take terfenadine, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.

Terfenadine is in the FDA pregnancy category C. This means that it is not known whether terfenadine will harm an unborn baby. Do not take this medication without first talking to your doctor if you are pregnant. It is not known whether terfenadine passes into breast milk. Do not take terfenadine without first talking to your doctor if you are breast-feeding a baby.