Generic name: Astemizole.

Hismanal is an antihistamine. Antihistamines block the effects of histamine, a body chemical that causes swelling and itching. 

Quick Facts About Hismanal


Used to treat hay fever and chronic hives.

Hismanal Dosage

Should take on an empty stomach, 1 or 2 hours before meals. Adhere to prescribed dose; higher doses may cause dangerously irregular heartbeats.

  • Usual adult dose (and children 12 years and older): 10 milligrams (1 tablet) per day.
  • Usual child dose: not generally prescribed for children under 12 years.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Hismanal Side Effects

Overdose symptoms:

cardiac arrest, fainting, irregular heartbeat, seizures. If you suspect an overdose, immediately seek medical attention.

More common side effects: drowsiness, dry mouth, fatigue, headache, increase in appetite, weight gain.

Less common Hismanal side effects: asthma-like symptoms, burning/prickling/tingling skin, depression, diarrhea, dizziness, fluid retention, hepatitis, inflammation of the eyelids, itching, joint pain, muscle pain, nausea, nervousness, nosebleed, palpitations, sensitivity to light, skin rash, sore throat, stomach and intestinal pain. Rare side effect low blood pressure.


Do not take with erythromycin (PCE or E-Mycin) or ketoconazole (Nizoral); may cause serious heart problems.

Inform your doctor before combining Hismanal with:

antibiotics such as Flagyl; antifungal drugs such as Diflucan, Nizoral, Monistat and Sporanox; drugs that affect heart rhythms such as Vascor, Elavil, and Thorazine; macrolide antibiotics such as Zithromax, Biaxin, E-Mycin, and Tao.

Taking with food reduces effectiveness. 

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. Not known if Hismanal appears in breast milk.

No special precautions apply to seniors.

Not generally prescribed for children under 12 years.

  • Inform your doctor before taking Hismanal if you are currently being treated for lower respiratory tract disease (asthma) or liver or kidney disease.
  • Should not take if allergic to Hismanal.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Hismanal side effects, please contact your healthcare provider.