An allergy is a hypersensitive reaction to any of a number of substances. Allergies occur when the body’s immune system malfunctions, going into overdrive to help protect the body from a substance it sees as foreign. Allergies are very common in the United States. In fact, more than one-third of all Americans suffer from an allergy of one type or another. Common symptoms include nasal congestion, coughing, watery eyes, sneezing, fatigue, and headaches. Some allergies may cause hives or an itchy rash. Severe allergies can cause the blood pressure to drop to dangerously low levels, leading to anaphylactic shock and death.
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