Before taking Allegra, tell your doctor if you are also taking ketoconazole (Nizoral), or erythromycin (E-Mycin, E.E.S., Ery-Tab, Erythrocin).
There may be other drugs that can interact with Allegra. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.