What is the difference between a drug allergy and a drug intolerance?
A drug allergy is a rare condition in which the body's immune system responds to a drug and
causes adverse health effects. Mild drug allergies cause a rash or cough, while more severe
reactions may cause trouble breathing, low blood pressure, or a change in heartbeat. Severe
allergic reactions can be life-threatening. Penicillin and sulfa antibiotics cause allergic
reactions more often than most other drugs. If you've had a serious allergic reaction to a
medicine, you should not receive the same drug again - or others similar to it. Your doctor can
do a blood or skin test to confirm a drug allergy. If you react to a drug that you need to
take, your doctor may be able to desensitize you to the drug so that your body no longer reacts
A drug intolerance is different from a drug allergy, since it doesn't involve an immune reaction. A drug intolerance is an adverse effect from a drug, such as stomach irritation caused by taking aspirin. Common drug intolerances include drowsiness and stomach upset. If you have a drug intolerance, you may be able to continue with the drug by taking your dose with food or at bedtime, or if your doctor lowers your dose. Sometimes drug intolerances simply disappear as drug therapy continues. To make sure you use drugs safely, tell your doctor and pharmacist about any drug allergies or drug intolerances you have. In case of a severe allergic reaction to a drug, consider wearing a medical alert bracelet or necklace and carrying an alert card in your wallet that lists your drug allergies.
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