Phenergan is the trade name of the most common antihistamine used in Britain: promethazine. Promethazine is used all over the world as a first choice for hayfever and other allergic symptoms. It deserves special mention because it is used as a sedative preoperatively and also for children who are exhibiting sleep pattern difficulties. This latter use as a sedative is based on one of Phenergan’s side effects, which is drowsiness.
Basically Phenergan will suppress symptoms of allergy and is in no way a treatment or cure. It is best to try to treat the cause of an allergy rather than suppress the symptoms. If necessary, however, it can be used safely if taken short term. The same can be said for its sedative effects, and for children I would recommend that no more than three nights should be affected by promethazine without at least a one-week gap.