An allergy is a reaction of the body's immune system to a foreign substance, also called an allergen. The immune system produces substances that recognize and attempt to destroy the allergen, but in doing so release a substance that produces the symptoms of allergic reactions. Allergies to medications are fairly common but can be avoided to prevent serious complications.
Penicillin
Penicillin, a drug prescribed to treat bacterial infections, is one of the most common sources of drug allergies. The most common symptoms of a penicillin allergy include hives and rashes, itchy skin, facial swelling and wheezing. In severe cases, an anaphylactic reaction--a potentially life-threatening condition--may occur. Penicillin allergies are not present at birth but develop after an initial exposure to penicillin or over time, according to MayoClinic.com. A simple skin test in which a small amount of penicillin is injected under the skin can identify penicillin allergies. Mild reactions to penicillin can be treated with antihistamines. Anaphylaxis requires immediate treatment to keep the airways open and regulate blood pressure.
Cephalosporins
Cephalosporins are a class of antibiotics most often used in the treatment of bronchitis, cellulitis and pneumonia. Allergy symptoms include fever, skin reactions, and serum-sickness-like reactions, such as a rash and arthritis. Anaphylaxis reactions are rare with cephalosporin allergies, according to a 2001 review article in the New England Journal of Medicine. Individuals with a penicillin allergy are at an increased risk of also being allergic to cephalosporins.
Sulfonamides
Sulfonamides, also called sulfa drugs, refer to a group of medications used to treat a broad spectrum of bacterial infections. Symptoms of an allergic reaction vary, but most often result in a fever and rash. Sulfonamides can cause blood abnormalities and kidney problems when over used. However, in individuals allergic to penicillin or in battling penicillin-resistant bacteria, physicians may prescribe sulfonamides.
Aspirin
Reactions to aspirin have been known to cause severe asthma attacks, especially in those diagnosed with asthma or sinus problems, according to MayoClinic.com. Other symptoms include hives, itchy skin, and swelling of the lips, face, and tongue. In rare cases, aspirin allergies are life-threatening. Many over-the-counter (OTC) medications on the market include aspirin, so it is important to check medication labels and consult a physician if an allergy is suspected. People who are allergic to aspirin may be allergic to other nonsteroidal anti-inflammatory drugs as well, so it may be best to avoid them as well.
