Drug allergies are a group of symptoms caused by an allergic reaction to a drug (medicine).
Allergic reaction - drug (medication); Drug hypersensitivity; Medication hypersensitivity
A drug allergy involves an immune response in the body that produces an allergic reaction to a medicine.
The first time you take the medicine, you may have no problems. But, your body's immune system may produce a substance (antibody) against that drug. The next time you take the drug, the antibody may tell your white blood cells to make a chemical called histamine. Histamines and other chemicals cause your allergy symptoms.
Common allergy-causing drugs include:
- Drugs used to treat seizures
- Insulin (especially animal sources of insulin)
- Substances containing iodine, such as x-ray contrast dyes (these can cause allergy-like reactions)
- Penicillin and related antibiotics
- Sulfa drugs
Most side effects of drugs are not due to an allergic reaction. For example, aspirin can cause hives or trigger asthma without involving the immune system. Many people confuse an unpleasant, but not serious, side effect of a medicine (such as nausea) with a drug allergy.