The mechanism of action of antihistamines
Allergic reaction with various symptoms, causes Allergy, affects in the body begins to produce biologically active substances, the excess of which leads to allergic inflammation. These substances are many, but the most active is histamine, which in its ordinary state contains in fat cells and is biologically neutral. Becoming active under the action of the allergen, histamine causes appearance of such irritating and discomforting symptoms, such as skin rashes and itching, swelling and runny nose, conjunctivitis and redness of the eyes, spasm of the bronchi, lowering blood pressure, etc. Antihistamines prevent, reduce or eliminate symptoms of allergies by reducing the histamine release in blood or neutralizing it.
What are antihistamines
These drugs are divided into two groups. The first is traditionally used for the relief of allergic symptoms diphenhydramine, promethazine, suprastin, tavegil, diazolin and fenkarol, they are called preparations of the old generation. They all usually have one thing in common a side effect – cause drowsiness. The new generation of drugs include, for example, astemizole (hismanal) and claritin (loratadine). The main difference between these two groups of antihistamines that new generation drugs do not have a sedative effect and should take them once a day. True, the cost of these drugs is much higher than "classic".
Other pharmacological properties of antihistamines
In addition to the suppression and neutralization of histamine, these drugs possess other pharmacological properties that should be considered if you're buying them without a prescription. So, most of them have the ability to enhance the action of other drugs, so often as the gain of the anesthetic effect is used, for example, such a combination as analgin and Dimedrol. These drugs also enhance the effectiveness of drugs affecting the Central nervous system, so their joint reception can cause overdose and have unpredictable consequences.
Acute respiratory diseases of not recommended to take Allergy medications like diphenhydramine, promethazine, suprastin or tavegil. They also dry mucous membranes and make it more dense and viscous mucus produced in the lungs, not allowing her to cough up, which may increase the risk of developing pneumonia. There are other side effects of antihistamines, which are known only to specialists, so before you take something, consult your doctor.