Antibiotics are a class of drugs prescribed for the treatment of bacterial infections. Over the years, bacterial organisms have become resistant to different types of antibiotics as a result of misuse by patients, and over prescription by physicians. Antibiotics such as penicillins, cephalosporins, and sulfonamides are likely to cause allergic reactions resulting in different types of rashes. Speak with your physician, and make sure he or she is aware of any previous allergic reaction to antibiotics, since an individual allergy to one antibiotic, is more likely to have an allergic reaction to other antibiotic drugs.
Pencillin Rash
A drug rash is a common allergic symptom to antibiotics such as penicillin. This occurs when the immune system produces IgE antibodies, and recruits immune cells such as mast cells and basophils in response a penicillin/hapten complex. In addition, these immune cells release histamine, a chemical messenger that causes local swelling, and widening of blood vessels. According to UpToDate, rashes involved with raised and intensely itchy hives are a true indicator of an allergic reaction to penicillin. This type of rash is raised with white or red welts that can appear in different locations on the body, and disappear and reappear after a few hours. If you experience this type of rash, stop taking the medication, and speak with your physician about another type of antibiotic. If you are allergic to penicillin, you're probably allergic to all penicillin-related antibiotics, and should avoid using penicillin the future.
Maculopapular Rash
A maculopapular rash in 5 to 10 percent of children prescribed antibiotics such penicillin, amoxicillin and cephalosporin, and in some cases may cause fever and headaches. This rash typically appears one to two weeks after starting the medication, and begins as discreet red or pink spots on the trunk of the body. Gradually these red or pink spots cluster together, and merge to form sheets of flat, blotchy rashes that spread to the neck and limbs in a symmetrical pattern. Unlike a penicillin rash, a maculopapular rash does not change or disappear by the hour, and is non-raised or involved with hives. This type of rash resembles the rash of measles or rubella, and involves the entire surface of the body. If you have a low platelet count, this rash may appear purple or take on the appearance of bruises on the lower legs. Immediate cessation of the antibiotic resolves the rash in one to two weeks. Your physician may prescribe an oral antihistamine or topical corticosteroids to help relieve the itch.
Urticaria
Urticaria, also known as hives or a nettle rash is caused by the release of histamine from mast cells in response to antibiotics such as penicillin, tetracycline, sulphonamides and cephalosporin. Histamine is chemical messenger that causes swelling, itching and redness of the skin. Urticaria is characterized by red, raised spots with a pale center. The hives are typically itchy and swollen, and can vary in size. The hives typically appear within 24 hours of taking an antibiotic, and can appear anywhere on the body. In some cases, the hives may enlarge and merge together, and blisters may also appear in the eyes, and mouth. Since histamine causes increased vascular permeability, up to 50 percent of individuals with urticaria develop angioedema, or swelling in deep layers of the skin. Swelling of deeper layers of the skin typically involves the hands, eyelids, tongue, lips and feet. Since itching is the most troubling symptom of urticaria, second generation antihistamines such as loratadine and cetirizine are prescribed to alleviate the itch.
Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis
Stevens-Johnson Syndrome and toxic epidermal necrolysis are severe, adverse reactions to antibiotics containing sulfa, penicillin and barbiturates. The individual may initially experience non-specific symptoms such as a fever, headache, cough and body aches. Next, specific symptoms such a skin lesions appear on the trunk and face, as well as the palms and soles. These lesions quickly begin to blister, and can spread to the eyes, nose, mouth, genital areas. The top layers of the skin begins to peel away in large sheets, causing fluids to leak from the damaged areas. This condition is extremely dangerous since the disease progresses extremely fast, typically within three days and greatly increases the risk of deadly infections. The mortality rate for Stevens-Johnson Syndrome is 5 percent, and 30 to 35 percent with toxic epidermal necrolysis. Treatment involves immediate discontinuation of the drug, and hospitalization in the burn unit.
References
- "The New York Times"; A Guide to Smarter, Safer Antibiotic Use; Jane E. Brody; March 2011
- Drugs.com: Antibiotic Medication Allergy
- UpToDate; Allergy to Penicillin and Related Antibiotics; Roland Solensky, MD; August 2010
- DermNet NZ; Morbilliform Drug Reaction; Delwyn Dyall-Smith, MD
- Dr. Adrian Morris Surrey Allergy Clinic, London; Adrian Morris, MD; Urticaria, Hives, Nettle Rash and Angioedema
- "Dermatology Online Journal"; Treatment of Severe Drug Reactions: Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis and Hypersensitivity Syndrome; Pierre-Dominique Ghislain MD, Jean-Claude Roujeau MD; June 2002
