Remember that cough or cold remedies often contain antihistamines, so if you are taking these as well you need to work out your total dosage to make sure you don’t take more than the total recommended amount for any one period.Some people use antihistamines such as Phenergan and Vallergan as sedatives for their children, for example when they are travelling on a plane, but this can backfire as some children respond by becoming significantly more active (not a nice thing at 30,000 feet).
The alkylamines include brompheniramine (Dimetapp) and chlorpheniramine (Chlor-Trimeton.) These agents cause relatively little sedation, and are used primarily for treatment of allergic reactions.Consult more detailed references for further information.The second generation antihistamines have no central action, and are used only for treatment of allergic reactions. Cetirizine (Zyrtec) is a piperazine derivative, and has a slight sedative effect.Individual drugs may be effective in no more than 40% of patients, and provide 50% relief of allergic symptoms. A large number of additional reactions have been reported.Central nervous system reactions include drowsiness, sedation, dizziness, faintness, disturbed coordination, lassitude, confusion, restlessness, excitation, tremor, seizures, headache, insomnia, euphoria, blurred vision, hallucinations, disorientation, disturbing dreams/nightmares, schizophrenic-like reactions, weakness, vertigo, hysteria, nerve pain, and convulsions. Not all apply to every drug, and some reactions may not be drug related.hayfever (seasonal rhinitis), drug allergies, urticaria (induced by insect bites); injected antihistamine (chlorphenamine) is used as an adjunct to adrenaline in the treatment of anaphylaxis and angioedema; modern antihistamines (e.g.