Drug allergies
Allergic drug reactions account for 5% to 10% of all adverse drug reactions, with skin reaction being the most common form.
Penicillin and related antibiotics are the most common cause of drug allergies. Other common allergy-causing drugs include sulfa drugs, barbiturates, anticonvulsants, insulin preparations (particularly animal sources of insulin), local anesthetics such as Novocain, and iodine (found in many X-ray contrast dyes).
Little is known about drug allergies and few diagnostic tests are available. Many individuals may confuse an uncomfortable but not serious side effect of a medicine, such as nausea, with a drug allergy.
Symptoms
Most drug allergies cause minor skin rashes and hives. Other symptoms can include chest tightness, wheezing, nausea, vomiting, cramping, and swelling of the lips and joints. The most dangerous symptoms are low blood pressure, breathing difficulties, shock and loss of consciousness, all of which can be fatal.
With a drug allergy, the body becomes sensitized (the immune system is triggered) by the first exposure to the medication. The second or subsequent exposure causes an immune response, including the production of antibodies and release of histamine.
Treatment
Antihistamines usually relieve mild symptoms (rash, hives, itching).
Topical corticosteroids applied to the skin also may be recommended.
Bronchodilators may be prescribed to reduce asthma-like symptoms (moderate wheezing or cough).
The offending medication should be avoided.
Be sure to tell your health care providers about your drug allergies.
Source: National Institute of Allergy and Infectious Diseases
