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Terfenadine was withdrawn from the U.S. market in 1998.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Terfenadine was withdrawn from the U.S. market in 1998.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

How should I take terfenadine?

Take terfenadine as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.

Take each dose with a full glass (8 ounces) of water. Do not crush, break, or chew the tablets. Swallow them whole.

Terfenadine is usually taken twice a day, in the morning and the evening. Never take more of this medication than is directed by your doctor. If your symptoms are not being adequately treated, talk to your doctor.

Store terfenadine at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take only your next regularly scheduled dose. Do not take a double dose of this medication.

What happens if I overdose?

Seek emergency medical attention.

Symptoms of a terfenadine overdose include headache, drowsiness, irregular heartbeat, nausea, and vomiting.

What should I avoid while taking terfenadine?

Use caution when driving, operating machinery, or performing other hazardous activities. Terfenadine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities. Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while you are taking terfenadine.