Ketotifen is a potent antihistamine which exhibits strong H₁ receptor-blocking activity. In addition it has been shown to possess antianaphylactic and antiasthmatic properties through inhibition of releasing of chemical mediators from tissue mast cells and basophils, in particular histamine and the leukotrienes.

1. Prophylaxis of bronchial asthma: Ketotifen is indicated for the treatment of mild asthma, particularly in children and in adults who find inhaled treatment unacceptable.
2. Allergic rhinitis and conjunctivitis.

Although there in no evidence of any teratogenic effect, Ketotifen is not recommended during pregnancy. Ketotifen is excreted in breast milk, therefor mothers receiving Ketotifen should not breast - feed.

A reversible fall in the platelet count has been observed in a few patients receiving Ketotifen concomitantly with oral antidiabetics.
Ketotifen may potentiate the effects of other CNS depressant drugs such as alcohol, antihistamines, hypnotics and sedatives.

As for the antihistamines in general, drowsiness, sedation, tiredness, weight gain and dry mouth are the most common side-effects.
Dizziness, nausea and headache, exacerbation of asthma, bronchospasm and status asthmaticus may occur.

Ketotifen is taken by mouth 1mg twice daily with food, increased if necessary to 2mg twice daily; 0.5 to 1 mg at night may be preferable for the first few days of treatment if drowsiness is likely to be a problem.
Children over 2 or 3 years may be given 1mg twice daily and between 6 months and 3 years suggested 0.5mg twice daily.

1. Martindale, the complete drug reference 32nd edition.
2. Therapeutic drugs, 2nd Edition.