Antihistamines are a group of drugs used to treat allergy symptoms. They are the most widely used allergy remedy on the market and some are available without a prescription. As the name states, an antihistamine blocks the action of a chemical produced in the body called histamine. Histamine is fairly ubiquitous throughout the body and both regulates inflammation during an immune response and acts as a neurotransmitter, relaying messages between neurons in the brain.
During an allergy attack, the immune system responds to the presence of allergens in the body in part by initiating a release of histamine from special cells that store it. Histamine in turn latches onto receptors found in muscle and skin cells to trigger a response. Part of this response involves a constriction of the airways in the lungs, a widening of the blood vessels, a separation of skin cells (resulting in hives and itching), general inflammation, headache and nausea. It’s easy to see that these biological changes result in many of the classical allergy symptoms. The body’s attempt to ward off a potentially dangerous intrude often results in misery for the allergy sufferer!
Fortunately for those afflicted with allergies, oral antihistamines offer a simple and well-tolerated solution to the discomfort. Antihistamines reduce or eliminate the body’s ability to achieve the histamine response necessary to bring about allergy symptoms. They achieve this by binding to the same sites histamines target, but without causing the same effect. With their receptor sites occupied by antihistamines, molecules of histamine are prevented from doing their job and the would-be allergy sufferer can go about their day sniffle-free.
Antihistamines were first discovered in the 1930′s, and many different varieties have emerged since then. Many of the first-generation antihistamines, such as the popular Diphenhydramine, have mild side effects such as sedation or dizziness due to their action on receptors in the brain. Sometimes this is desired, as in the case of trying to sleep at night with allergies, but antihistamines with this side effect are often paired with a wakefulness-promoting agent to counteract drowsiness. There are newer-generations of antihistamines on the market that carry with them less side-effects, due to their lessened ability to cross the blood-brain barrier and act upon receptors.
It’s important to note that antihistamines work best if taken before exposure to allergens. There are a number of products available indicated for daily use as a preventative measure, and are a popular choice amongst those who suffer from seasonal allergies.by