Drug Allergy vs Intolerance

Chat with Pharmacy Staff

Question

What is the difference between a drug allergy and a drug intolerance?

Answer

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 to it.

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.

Back to Pharmacist FAQs

If you're looking for more specific answers to specific questions, ask a Walgreens pharmacist here.

DISCLAIMER:
Answers to questions regarding information about medications or health conditions are not for diagnostic or treatment purposes and are not conclusive as to the presence or absence of any health condition. Consult your physician for diagnosis and treatment of your medical condition. The information provided is not a substitute for medical advice. Advances in medicine may cause this information to become outdated, invalid or subject to debate. Professional opinions and interpretations of the scientific literature may vary. Walgreens' terms of use and general warranty disclaimer apply to all services provided. If you are in need of immediate medical attention, contact your physician, poison control center or emergency medical professional. If you need to speak with a pharmacist for non-emergency matters, contact your local Walgreens pharmacist or call a Walgreens.com pharmacist toll-free at 1 (877) 250-5823.