When the body is attacked by a foreign substance, the immune system produces antibodies to destroy it to protect you from becoming sick. Allergies are responses from your immune system that occur when a foreign body triggers antibody release, even if it is not harmful. These allergy-causing substances are called allergens.
Signs of an allergic reaction include inflammation of the skin, airways, digestive system or sinuses. The severity of allergies can range from minor irritation to a life-threatening emergency called anaphylaxis.
Allergies are specific to each individual. The allergens that affect one person may not cause any reaction in another.