An allergy is a hypersensitive reaction of the body when it comes into contact with a substance that is in fact harmless .An allergy is certain cause occurs suddenly and is predictable . The hypersensitive response comes from the natural immune system and ranges from a slightly uncomfortable feeling to a fatal anaphylaxis. Light allergies are part everyday life . Allergic rhinitis , hay fever characterized by runny nose ,red eyes and itchiness. Food allergy causes vomiting, watery stools, rashes, substances that causes allergy often are proteins in food such as milk, wheat, beef, eggs, and so on the allergy, such as blood tests, skin tests etc. Ocular allergy includes several clinically different conditions that can be considered as hypersensitivity disorders of ocular surface. Ocular allergy symptoms are often but not always associated with other allergic manifestation mostly rhinitisSometimes the eyes can react to other allergens that donâ€™t necessarily come in direct contact with the eye, such as specific type of food material.