Science Behind Allergy Medication

Over fifty million Americans have allergies and thirty-two million have food allergies. You probably know one of those people or are one yourself. But why does allergic reaction occur? An allergic reaction occurs when your immune system overreacts to a food or a substance in a food, thus identifying it as a danger and triggering a protective response. Symptoms of a food allergy can range from mild to severe, with the most severe allergic reaction being anaphylaxis. During an anaphylaxis shock, Epinephrine may be life-saving if administered to a person as quickly as possible. However, in minor cases, prescribed antihistamines such as diphenhydramine (Benadryl) may help reduce symptoms.

What is the science behind an EpiPen?
The first-line treatment for anaphylaxis is epinephrine (adrenaline). It is available by prescription in an auto-injector named EpiPen. Epinephrine works by reversing the symptoms of anaphylaxis. For example, when you inject an Epipen on the thigh, a person's blood pressure decreases during an anaphylactic reaction because the blood vessels relax and dilate however the epinephrine causes the blood vessels to constrict, thus raising blood pressure. Epinephrine is the synthetic form of the naturally occurring sympathomimetic amine with vasoconstricting (constriction of blood vessels thus raising blood pressure), intraocular pressure-reducing, and bronchodilating activities (An expansion of the air passages through the bronchi of the lungs). Additionally, Epinephrine elevates the blood sugar levels by increasing the hydrolysis of glycogen to glucose in the liver, and at the same time, it begins the breakdown of lipids in adipocytes (a cell specialized for the storage of fat). In all, Epinephrine has a suppressive effect on the immune system.

What is the science behind antihistamines?
Antihistamines reduce or block histamines, therefore they can stop allergy symptoms. It works well to relieve symptoms of different types of allergies, including seasonal, indoor, and food allergies. Antihistamines block H1 histamine receptors. They replace histamine at receptor sites  (proteins that receive signals for a cell) at which it becomes bound in various susceptible tissues. Thus it prevents histamine-triggered reactions under conditions like food allergies. 

In terms of the difference between antihistamines and epinephrine, it is essential to note that epinephrine is not a long-term medication for allergies, and should not be a substitute for allergy medications like antihistamines.

By: Vasundhara Kulkarni
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