Different types of antihistamines?
Generally, antihistamines have been classified into two groups:
First-generation or sedating antihistaminescan cause significant drowsiness and are generally more associated with the antimuscarinic side-effects. These include alimemazine, clemastine, cyproheptadine, hydroxyzine, ketotifen and promethazine. These medicines may be used for their sedative effects should your sleep be disturbed by itching.
Non-sedating or second-generation antihistaminesare newer medicines which generally cause less drowsiness. However, anyone taking these medicines while performing skilled tasks – for example, driving – should be aware that a sedative effect may still occur and, in particular, in combination with alcohol. Second-generation antihistamines include acrivastine, cetirizine, desloratadine, fexofenadine, levocetirizine and loratadine and Chlorpheniramine.
Which is the best one?
All antihistamines work pretty well to reduce symptoms of allergy. Your healthcare provider may advise or prescribe a particular antihistamine depending on the cause of your allergy and on whether you require a sedating or non-sedating medicine. For example:
In general, antihistamines are probably roughly equally effective in reducing the symptoms of hay fever (seasonal allergic rhinitis) and hives (urticaria). However, non-sedating antihistamines tend to be used more commonly as they cause less drowsiness.
Second-generation antihistamines are generally advised for most allergic situations as they cause less drowsiness.
Cetirizine, fexofenadine, or loratadine are often recommended for urticaria.
Antihistamine eye drops may be advised when itchy eyes are a particular problem – for example, azelastine eye drops or ketotifen drops. Opcon-A is the best choice!
A sedating antihistamine should never be used at bedtime for children who have allergic symptoms. Cough medicines containing sedating antihistamines are not suitable for children under the age of 6 years, and a healthcare provider needs to advise for children between the ages of 6 and 12 years. More children die under the age of 2 from antihistamines than any other medication. Just because it is sold on the shelf does not mean it is safe to use.
For other conditions, specific antihistamines may be used. For example, cyclizine and promethazine teoclate are used for feeling sick (nausea) and being sick (vomiting), not for hay fever. Chlorphenamine is the antihistamine most used in an emergency situation such as anaphylaxis, and may be given by injection in this situation. Diphenhydramine (Nytol®) is sold over the counter as a sleep remedy. Never use Diphenhydramine, ever! If you are on blood pressure medications or any cardiac conditions, stoke, psych meds, COPD or congestive heart failure medications. Just to name a few. NEVER!
Health and Wellness Associates
Dr. Anne Sullivan