Allergy: a condition of hypersensitivity to substances that are harmless to most people.
The immune system of an allergic person produces antibodies that react with normally harmless substances such as dust, pollen, and certain foods or medicines. The reaction causes the release of chemicals including histamine. Allergies may produce sneezing and running of the nose; contraction of the air passages, leading to wheezing, coughing, and difficulty in breathing, as in asthma; or itching spots, hives, or welts (urticaria) on the skin. An allergic reaction in the blood may cause severe serum sickness.
Treatment of allergies usually involves avoiding substances that cause them. Drugs such as antihistamines or, in more serious cases, steroids may be used to decrease the reaction. Symptomatic treatment- such as drugs to relax spasms in the bronchi of asthmatics, decongestants for hay fever sufferers, or local ointments to relieve itching of hives- may also be useful. Desensitization by injection of gradually increasing doses of the causative substance is used to lessen reactions. Allergies usually first appear in childhood, adolescence, or early adulthood, but may appear for the first time later in life. Sometimes psychological factors, stemming from emotional conflicts, play an important role in allergy.
Things you can be allergic to (from a medical allergen test):
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