An allergic reaction is your body's response to an allergen. Reactions can vary from person to person, and from allergen to allergen. They can affect many systems of your body, and they can range from mild to severe.
Some allergens affect the airways. When you breathe in pollen or pet dander, for example, you may experience sneezing, a runny nose and itchy, red, watery eyes. This is commonly called "hay fever." If you are allergic to a food, eating it may result in tingling and swelling of your lips, mouth and throat. Your skin may break out in hives. If you are allergic to insect stings, your response may involve swelling, itching and hives on your skin. You may have trouble breathing. If you are allergic to a medication, it may cause a rash or hives, itchy skin, swelling and breathing problems.
The most serious type of allergic reaction is called "anaphylaxis." With it, your body can go into shock. Your blood pressure may drop, and your pulse may weaken. You may experience nausea, vomiting and lightheadedness. You may have a rash and shortness of breath. You may lose consciousness. Anaphylaxis is a medical emergency. Without prompt treatment, it can be fatal.
Many allergic reactions can be treated with over-the-counter medications. You may benefit from antihistamines, eye drops, or creams for your skin, depending on your needs. Anaphylaxis may be treated with an epinephrine autoinjector and immediate emergency care. Your healthcare provider can create a care plan that is right for your needs.