Drug Allergy

Drug allergies are an allergic reaction to medications. It’s when your body’s immune system overreacts to medications. Your body develops a sensitivity to one of the substances in the medication and “remembers” it as a harmful foreign invader, like bacteria or viruses. The next time you ingest that drug, your immune system releases antibodies to remove it from your body.

A drug allergy can be deadly. If you or a loved one have severe drug allergy symptoms, including swelling of your tongue or throat, trouble breathing, a fast heartbeat, lightheadedness or unconsciousness, you must act quickly:

• Call 911 or your local emergency number.
• Go to your nearest emergency room (ER) as soon as possible.

What is an example of a drug allergy?

Any drug can cause an allergic reaction. But the most common medications that cause an allergic reaction include:

• Antibiotics, including penicillin.
• Sulfa drugs (a type of antibiotic that contains sulfonamides).
• Nonsteroidal anti-inflammatory drugs (NSAIDs), which include ibuprofen (Advil®), aspirin (Bayer®) and naproxen (Aleve®).
• Acetaminophen (Tylenol®).
• Opiates, which include morphine and codeine.
• Chemotherapy drugs.
• Antiseizure medications.
• The contrast material (dye) that some X-rays use to get a clearer image.

What is the most common drug allergy?

Penicillin is the most widely reported drug allergy. Around 10% of people report being allergic to penicillin, though recent studies show that you may outgrow penicillin allergies with time.

How common are drug allergies?

An adverse drug reaction is an unexpected or undesirable reaction to a medication. Drug allergies account for less than 10% of all adverse drug reactions. Side effects account for more than 90% of all adverse drug reactions. Side effects are possible reactions to a medicine that don’t involve your immune system.