Allergy

An allergy occurs when the body’s immune system overreacts to a substance, called an allergen, that is usually harmless to most people. If you have an allergy, your immune system mistakes an otherwise harmless substance as an unwelcome invader. These allergens can trigger a variety of symptoms including nasal congestion or itching, ear pressure, sinusitis, sneezing, runny nose, itchy or watery eyes and coughing. Less common allergy symptoms are headaches, loss of taste or smell, low productivity or poor concentration, fatigue and sleep disturbances.