A drug allergy is a reaction by your immune system. If you are allergic to a drug, even a small amount of the drug can trigger a reaction. These reactions range from mild to life-threatening.
Your immune system treats a drug as a foreign substance and tries to protect you from it. The drugs most likely to cause these problems are:
Some people are allergic to penicillin. Anyone can develop an allergy to penicillin after exposure to it. Having an allergy to penicillin does not mean you are allergic to all antibiotics.
The most common symptoms are itching, redness, swelling of the skin, welts, and a runny nose. Symptoms of a drug allergy can occur within minutes of taking the first dose, or they can begin several days after taking the drug. About half of all allergic reactions occur 1 week after starting the drug. Most symptoms go away 3 to 5 days after you stop taking the drug.
Anaphylaxis is a life-threatening allergic reaction. This reaction is sudden, severe, and involves the whole body. Symptoms of anaphylaxis include:
Your health care provider will ask about your symptoms and the drugs you have taken. Tell your provider about all your medicines (prescription, nonprescription, supplements, natural remedies, and vitamins).
If you have an allergic reaction, your provider may recommend that you see an allergy specialist for testing. For example, if a penicillin allergy is suspected, the best way to confirm it is with a skin test.
Anaphylaxis is life-threatening. If you think you are having severe allergic reaction, get emergency medical care or call 911 for help. A severe or life-threatening reaction may require an injection of epinephrine (also called adrenaline) or a corticosteroid, such as hydrocortisone. A mild reaction may be treated with an antihistamine.
The effects of the allergic reaction last from several minutes to hours, depending on how much of the drug you took and the severity of your allergy.
To prevent allergic reactions in the future, you must avoid taking the drug that caused the reaction. If you have had a severe allergic reaction, wear a medical alert bracelet at all times. Tell all health care providers who treat you if you have ever had an allergic reaction to any medicine. Be sure to check all labels for the names of these drugs before taking any medicines or natural remedies.
Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.
HIA File ALL3107F.HTM Release 9.0/2006
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