An allergy is an abnormal reaction to a foreign but ordinarily harmless substance called an allergen. The immune system produces substances called antibodies. An allergic reaction occurs when the immune system produces antibodies that identifies an allergen as harmful, even though it is not. This can cause symptoms in the nose and/or eyes, resulting in allergic rhinitis (hay fever) and/or conjunctivitis (watery, red or swollen eyes); skin resulting atopic dermatitis e.g. eczema, or hives (urticaria); lungs resulting in asthma. Stomach and bowl allergies can cause an allergic reaction in any area of the body. Commonly consumed foods that cause allergies are peanuts, seafood, dairy products and eggs. Types of airborne allergens are pollen, dust mites, mold and animal fur. Insect stings from bees or wasps, and latex substances also cause allergies. Most allergic reactions are mild to moderate, and do not cause major problems, but the severity varies from person to person and can range from minor irritation to anaphylaxis (a life-threatening condition that can cause loss of consciousness, a decrease in blood pressure and severe shortness of breath). The best way to avoid an allergic reaction is reduce exposure to the allergen. Most allergies can't be cured, but there are medications that can help to relieve symptoms. e.g. antihistamines (block histamine release), intranasal corticosteroid nasal sprays (INCS) (treat moderate to severe allergic rhinitis), combination therapies (INCS and antihistamine), Medicated eye drops, Adrenaline/epinephrine (first aid emergency treatment of life threatening severe allergic reactions). Allergen immunotherapy (also known as desensitization) is an alternative treatment for allergies. It involves long-term exposure to gradually increasing amounts of allergen extracts, by injections or by sublingual tablets, sprays or drops.