Allergy Medications

Before reading this text about basic allergic medications, I advise to read the text about allergy, which is dedicated to allergic reactions, their mechanism and specific subtypes. The most commonly used drugs to treat allergy are antihistamines. Other drugs are focused on therapy of more serious conditions.


Antihistamines are common anti-allergic drugs. Their name is derived from their ability to block effects of a compound known as histamine. Histamine is released from certain cells after contact of our immune system with an allergen (any allergy-inducing substance). Blocking the effect of histamine also suppresses the whole allergic reaction. Usage of histamines has a long history and there have been developed more generations of these drugs. Newer generations inhibit allergy more effectively, while having less side effects than their predecessors.

First generation of antihistamines

These drugs have stronger side-effects. First generation of histamines includes for example substances known as dimetindene and bisulepin. The side-effects include mainly sedation. The persons using these drugs should not perform any activity that requires increased attention, for example driving motor vehicles. For the same reason, first generation of antihistamines should not be combined with alcohol. Bisulepin is commonly used in hospitals before radiological examinations with administration of contrast agent. Bisulepin protects from any contrast-induced allergic reaction and it also calms the patient and suppresses anxiety. In addition, bisulepin decreases skin itching, which is also frequent indication of its use. When used in children, first generation of antihistamines may cause absolutely opposite effects - restlessness, insomnia, tremor, etc. Besides affecting the nervous system, these drugs may cause dry mouth, or palpitations.

Second generation of antihistamines

This group of commonly used antihistamines includes substances like cetirizine and loratadine. The advantage of these drugs is their minimal sedative effect.

Third generation of antihistamines

The most modern antihistamines include for example substances such as levocetirizine and desloratadine. Their anti-allergic effects are very strong and adverse effects minimal.

Other allergy drugs

Antihistamines are not suitable for severe allergic reactions, including the anaphylactic shock. In such case, the patient is usually treated with high doses of corticosteroids that can be applied into the muscle or even intravenously. Quite special drug, which is used in severe anaphylactic shock, is the epinephrine. Corticosteroids, due to their numerous side-effects, should be rather used in acute condition and they are not suitable for chronic therapy.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources