Learn about different types of allergies, allergic reactions, their types, symptoms, and severity. Allergy symptoms can range from mild to severe, even life-threatening. Find out what treatments and prevention tips can help. What happens when you have an allergic reaction? Allergists recognize four types of allergic reactions: Type I or anaphylactic reactions, type II or cytotoxic reactions, type III or immunocomplex reactions and type IV or cell-mediated reactions. Find out about allergies, including typical symptoms, common allergies, when to get emergency medical help and allergy testing and treatments. Allergic reactions (hypersensitivity reactions) are inappropriate responses of the immune system to a normally harmless substance. Soaps, latex, and metals may trigger an allergic skin rash (contact dermatitis). Here are images of allergic skin reactions and how to treat them at home. Allergic reactions can affect your eyes, skin, breathing or more. If you were having one, would you know it? WebMD tells you what you need to know. In this article, we take a close look at a range of treatments for allergic reactions, depending on a person’s symptoms and their severity, including anaphylaxis. What is an allergic reaction? Allergic reactions are a set of symptoms that happen after you touch, inhale or eat something you’re allergic to. They can also happen after a bee sting. Examples of allergens that can set off allergic reactions include pollens, pets, dust, foods and medications. When you touch, inhale or eat something you’re allergic to, your body thinks it’s harmful and reacts to try to get rid of it. This can cause minor reactions like itching, sniffling and sneezing. But in some cases, allergic reactions can lead to life-threatening airway swelling and low blood pressure (anaphylaxis).