Note: This document contains side effect information about terfenadine. Some dosage forms listed on this page may not apply to the brand name Seldane.

Applies to terfenadine: oral tablet.

Cardiovascular

Terfenadine use may cause prolongation of the QT interval. Most cardiovascular events related to terfenadine (the active ingredient contained in Seldane) 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 (the active ingredient contained in Seldane) has not been demonstrated to cause significant drowsiness, sedation, or impaired psychomotor skills.^[Ref]

Gastrointestinal

Gastrointestinal effects of terfenadine (the active ingredient contained in Seldane) are rare and include nausea and dry mouth.^[Ref]

Genitourinary

A study of the effects of terfenadine (the active ingredient contained in Seldane) 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]

Hepatic

Acute hepatitis, cholestatic hepatitis, and jaundice have been reported rarely in patients taking terfenadine (the active ingredient contained in Seldane) Hepatic dysfunction has been reversible upon discontinuation of the drug.^[Ref]