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Astemizole Side Effects

Applies to astemizole: oral tablet.


Astemizole was withdrawn from the U.S. market in 1999.

Do not take astemizole (Hismanal) with any of the following medicines: antifungal drugs such as ketoconazole (Nizoral) and itraconazole (Sporanox); antibiotics such as erythromycin (E.E.S., E-Mycin, Ery-Tab), clarithromycin (Biaxin), and troleandomycin (TAO); the malaria medicine quinine (Quinamm); or the medicine nefazodone (Serzone).

Take astemizole on an empty stomach, 1 hour before or 2 hours after eating food.

Do not take astemizole with grapefruit or grapefruit juice. Grapefruit products may increase amount of astemizole available in your body, which could lead to dangerous side effects.

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

Other, less serious side effects may be more likely to occur. Continue to take astemizole and talk to your doctor if you experience

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 astemizole: oral tablet.


Cardiovascular system adverse effects have been associated with the use of astemizole. Adverse effects reported include dizziness, syncopal episodes, palpitations, ventricular arrhythmias (including torsades de pointes), cardiac arrest, and cardiac death.[Ref]

Astemizole and its predominant metabolite, desmethylastemizole, have been associated with prolongation of the QT interval. Most cardiovascular events related to astemizole occur in patients with higher than normal astemizole serum concentrations (either due to ingesting more than the recommended dose of 10 mg once daily or due to reduced elimination) or in patients at risk for cardiac events. Macrolide antibiotic and azole antifungal agents may inhibit the metabolism of astemizole, resulting in QT interval prolongation. Patients with liver dysfunction are also at risk due to decreased metabolism of the drug. Other predisposing factors 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]

Nervous system

Nervous system adverse effects associated with astemizole are rare. Headaches may occur in approximately 7% of treated patients. Astemizole has not been shown to cause significant drowsiness, sedation, or impair psychomotor skills. Increased appetite and weight gain has been reported in approximately 4% of patients.[Ref]


Gastrointestinal effects of astemizole are rare and include nausea and dry mouth.[Ref]


Rare cases of anaphylaxis, including anaphylactic shock, have been reported.[Ref]


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3. (1992) "Safety of terfenadine and astemizole." Med Lett Drugs Ther, 34, p. 9-10

4. (2002) "Product Information. Hismanal (astemizole)." Janssen Pharmaceuticals

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8. Sakemi H, VanNatta B (1993) "Torsade de pointes induced by astemizole in a patient with prolongation of the QT interval." Am Heart J, 125, p. 1436-8

9. Saviuc P, Danel V, Dixmerias F (1993) "Prolonged QT interval and torsade de pointes following astemizole overdose." J Toxicol Clin Toxicol, 31, p. 121-5

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11. Goss JE, Ramo BW, Blake K (1993) "Torsades de pointes associated with astemizole (hismanal) therapy." Arch Intern Med, 153, p. 2705

12. Rao KA, Adlakha A, Vermaansil B, Meloy TD, Stanton MS (1994) "Torsades de pointes ventricular tachycardia associated with overdose of astemizole." Mayo Clin Proc, 69, p. 589-93

13. Smith SJ (1994) "Cardiovascular toxicity of antihistamines." Otolaryngol Head Neck Surg, 111 Suppl, p. 348-54

14. Salata JJ, Jurkiewicz NK, Wallace AA, Stupienski RF, Guinosso PJ, Lynch JJ (1995) "Cardiac electrophysiological actions of the histamine h-1-receptor antagonists astemizole and terfenadine compared with chlorpheniramine and pyrilamine." Circ Res, 76, p. 110-9

15. Berul CI, Morad M (1995) "Regulation of potassium channels by nonsedating antihistamines." Circulation, 91, p. 2220-5

16. Desager JP, Horsmans Y (1995) "Pharmacokinetic pharmacodynamic relationships of h-1-antihistamines." Clin Pharmacokinet, 28, p. 419-32

17. Heidemann SM, Sarnaik AP (1996) "Arrhythmias after astemizole overdose." Pediatr Emerg Care, 12, p. 102-4

18. Woosley RL (1996) "Cardiac actions of antihistamines." Annu Rev Pharmacol Toxicol, 36, p. 233-52

19. Vorperian VR, Zhou ZF, Mohammad S, Hoon TJ, Studenik C, January CT (1996) "Torsade de pointes with an antihistamine metabolite: potassium channel blockade with desmethylastemizole." J Am Coll Cardiol, 28, p. 1556-61

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23. Simons FER, Fraser TG, Reggin JD, Simons KJ (1996) "Comparison of the central nervous system effects produced by six h-1-receptor antagonists." Clin Exp Allergy, 26, p. 1092-7

24. Juniper EF, White J, Dolovich J (1988) "Efficacy of continuous treatment with astemizole (Hismanal) and terfenadine (Seldane) in ragweed pollen-induced rhinoconjunctivitis." J Allergy Clin Immunol, 82, p. 670-5

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.