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Allergies Health Center

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Blocking Allergy Symptoms: How Pretreatment Works

Tackle allergies before they start, and you could be breathing a lot easier.
WebMD Feature

For lots of people, allergy treatment is reactive. You get stuffed up, your eyes water, and then you go to the medicine cabinet for relief. But many doctors say that we’ve got it the wrong way around. Instead, we should be taking the medicine before we have symptoms. Call it allergy pretreatment.

“We always tell people to start taking medicine before the allergy season begins,” says Jonathan A. Bernstein MD, an allergist and professor of clinical medicine at the University of Cincinnati. “People often come to me in the middle of the allergy season, and they’re already a mess. Once the symptoms start, they can be like a runaway train.”

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By waiting, you could be risking more than mild discomfort. Once allergy symptoms start, you might need more heavy-duty medicine to get them under control. In some people, allergy symptoms quickly turn into allergic sinusitis and more serious problems. That requires even more intensive treatment.

So the key to getting through the allergy season is to have a good defense. By arming yourself with medicine before the trees unleash their pollen -- or before you go visit your sister and her five cats -- you can save yourself a lot of suffering. How does allergy pretreatment work? Here are the answers.

Understanding Allergy Symptoms

Basically, an allergy symptom is the result of your immune system overreacting. It mistakes a harmless substance (like pollen or animal dander) for something more sinister (like a germ or virus) and attacks it. Common allergy symptoms -- like a runny nose -- are collateral damage, side effects of the immune system’s battle with an allergen.

After exposure to an allergen, the immune system releases the chemical histamine into your system. The histamine travels through your blood and latches onto histamine receptors on other cells. Once attached, the histamine causes the cells to swell. This inflammation causes many familiar allergy symptoms. Antihistamine drugs work by blocking the histamine from affecting these cells.

“By taking medicine early, you can prevent the inflammation from starting,” Bernstein tells WebMD. “The drugs block the histamine receptors and the histamine can’t bind with the cells.” Hence, no inflammation and no symptoms -- or at least fewer symptoms.

But if you take the drug after you have allergy symptoms, the histamine has already latched on. It’s already triggered the inflammatory process. Your body has already mobilized for a fight. It can be hard to get it to calm down again. It’s much easier to prevent the reaction than to try to stop it after the fact.

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