Allergy(एलर्जी ), Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment.These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis.Symptoms may include red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, or swelling. Food intolerances and food poisoning are separate conditions. Common allergens include pollen and certain food.Metals and other substances may also cause problems. Food, insect stings,and medications are common causes of severe reactions .Their development is due to both genetic and environmental factors.The underlying mechanism involves immunoglobulin E antibodies (IgE), part of the body's immune system, binding to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine. Diagnosis is typically based on a person's medical history. Further testing of the skin or blood may be useful in certain cases.Positive tests, however, may not mean there is a significant allergy to the substance in question.
Skin allergies may be a sign or symptom of an allergy. They may also be the direct result of exposure to an allergen.
For example, eating a food you’re allergic to can cause several symptoms. You may experience tingling in your mouth and throat. You may also develop a rash.
Contact dermatitis, however, is the result of your skin coming into direct contact with an allergen. This could happen if you touch something you’re allergic to, such as a cleaning product or plant.
Types of skin allergies include:
Rashes are one of the most common symptoms of a skin allergy.