Different prescription drugs can cause different types of allergic reactions, and some of them may even cause more than one type of reaction. An allergic reaction can develop for various reasons. At times, it is because the white blood cells are attacking pieces of the drug that are located in the skin. Other times, it can be the result of mast cells and basophils releasing substances or can even be due to antibodies attacking the drug.
Stevens-Johnson Syndrome
Sulfonamides, anticonvulsants, nonsteroidal anti-inflammatory drugs and allopurinol can cause an allergic reaction called Stevens-Johnson syndrome. People with this reaction have very large, painful blisters, as well as lesions on their skin that look like a "target." Gently rubbing the skin can cause the top layer to separate from the rest, as described by Ben Chlapek, D.O., of the Department of Emergency Medicine at the Scott and White Memorial Hospital in "Current Diagnosis & Treatment: Emergency Medicine." Physicians are not sure how this allergic reaction develops, but they hypothesize that the white blood cells, which normally attack foreign substances, see pieces of the prescription drug that are inside of the skin cells as foreign and are trying to attack the drug.
Anaphylaxis
Streptokinase, insulin and beta-lactam antibiotics can cause anaphylaxis, according to Peter Delves, Ph.D., of the Department of Immunology and Molecular Pathology at the University College London in "The Merck Manual for Healthcare Professionals." These medications make antibodies on mast cells and basophils tell the cells to release the substances inside them. These substances make the blood vessels get bigger, but the passages in the lungs and intestines smaller. People in an anaphylactic allergic reaction may sneeze, wheeze, and have a runny nose, diarrhea and cramps. They will also have a low blood pressure, a rapid heartbeat, and can go into shock within a matter of minutes, develop seizures and even die.
Urticaria
Urticaria is the medical terminology for hives. These are large, red, itchy areas on the skin that may disappear in a matter of hours. Penicillin and cephalosporins can cause this type of allergic reaction. It develops because the mast cells and basophils release their substances into the skin. Similar to anaphylaxis, the cells release these substances because antibodies make them do so. Infliximab and rituximab can also cause hives, but hives develop in their case because antibodies form against the drugs, as explained by Klauss Wolff, M.D., Chief Emeritus of the Dermatology Service at the General Hospital of Vienna in "Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology."
Angioedema
Penicillin, captopril and calcium-channel blockers can cause angioedema. These are large, swollen areas that involve the skin and the tissues just underneath the skin. Sometimes, people may develop urticaria, or hives, and angioedema as an allergic reaction to prescription drugs. Some people develop angioedema without hives. This reaction develops because the mast cells and basophils release their substances into the deep layer of the skin and the tissues underneath. People may develop swollen areas in their lips, face, arms, legs and even genital areas. If their tongue or throat gets swollen, it can be life-threatening because this can block the airway, explains Robert MacNeal, M.D., of the Section of Dermatology at the Dartmouth Hitchcock Medical Center in "The Merck Manual for Healthcare Professionals."
References
- "Current Diagnosis & Treatment: Emergency Medicine;" C. Keith Stone, M.D., Roger Humphries, M.D.; 2008
- "Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology;" Klauss Wolff, M.D., Richard Johnson, M.D.; 2009
- The Merck Manual for Healthcare Professionals: Atopic and Allergic Disorders
- The Merck Manual for Healthcare Professionals: Urticaria
