Allergies occur when your immune system reacts to a foreign substance — such as pollen, bee venom or pet dander — or a food that doesn’t cause a reaction in most people.

Allergy symptoms, which depend on the substance involved, can affect your airways, sinuses and nasal passages, skin, and digestive system. Allergic reactions can range from mild to severe. In some severe cases, allergies can trigger a life-threatening reaction known as anaphylaxis.

There are few types of allergies symptoms such as hay fever, food allergy, an insect sting allergy, drug allergy, atopic dermatitis.