<p>It is important to continue the previous treatment for a minimum of two weeks after starting Ketotifen to avoid the possibility of exacerbation of asthma. This applies specially to systemic corticosteroids and ACTH because of the possible existence of adrenocortical insufficiency in steroid dependent patient. If inter current infection occurs, Ketotifen treatment must be supplemented by specific antimicrobial therapy. During the first day of treatment with Ketotifen, reactions may be impaired and patients should be warned not to take charge of vehicle or machinery until the effect of Ketotifen treatment on the individual is known. Patients should be advised to avoid alcoholic drinks. Ketotifen may potentiate the effects of sedatives, hypnotics, antihistamines and alcohol.</p>