Allergic reaction: Overview
An allergic reaction is an excessive response from your immune system to a medicine, chemical, food, insect bite, or other substance. A reaction can range from mild to life-threatening. Some people have a mild rash, hives, and itching or stomach cramps. In severe reactions, swelling of your tongue and throat can close up your airway so that you cannot breathe.
Allergic reaction
An allergic reaction is an overreaction of the immune system to a substance called an allergen. Allergens include chemicals, foods, medicines, mold, plants, and pollen.
Symptoms of an allergic reaction can range from mild and annoying to severe and life-threatening.
- Allergens can affect different tissues in the body, such as the airways, eyes, gastrointestinal tract, nose, lungs, and skin.
- Some allergic reactions, such as hives or itching around an insect bite or where a plant or chemical touched the skin, affect only one area of the body.
- Other allergic reactions may affect the whole body, causing itching all over, swelling, fainting, belly pain, nausea, vomiting, or difficulty breathing.
- A severe allergic reaction (called anaphylaxis) can lead to shock and even death.
Allergic reactions may not occur the first time a person is exposed to an allergen. A person may become more sensitive to the allergen with each exposure.
How can you care for yourself when you have an allergic reaction?
- If you know what caused your allergic reaction, be sure to avoid it. Your allergy may become more severe each time you have a reaction.
- Take an over-the-counter antihistamine, such as cetirizine (Zyrtec) or loratadine (Claritin), to treat mild symptoms. Read and follow directions on the label. Some antihistamines can make you feel sleepy. Do not give antihistamines to a child unless you have checked with your doctor first. Mild symptoms include sneezing or an itchy or runny nose; an itchy mouth; a few hives or mild itching; and mild nausea or stomach discomfort.
- Do not scratch hives or a rash. Put a cold, moist towel on them or take cool baths to relieve itching. Put ice packs on hives, swelling, or insect stings for 10 to 15 minutes at a time. Put a thin cloth between the ice pack and your skin. Do not take hot baths or showers. They will make the itching worse.
- Your doctor may prescribe a shot of epinephrine to carry with you in case you have a severe reaction. Learn how to give yourself the shot and keep it with you at all times. Make sure it is not expired.
- Go to the emergency room every time you have a severe reaction, even if you have used your shot of epinephrine and are feeling better. Symptoms can come back after a shot.
- Wear medical alert jewelry that lists your allergies. You can buy this at most drugstores.
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