Penicillin allergies occur when the immune system overreacts and responds to the drug as if it were a harmful substance. The symptoms range from mild conditions such as rash and itchy skin to severe, life threatening anaphylactic reactions characterized by breathing difficulty, dizziness, weak pulse and loss of consciousness. According to the Leonard Davis Institute of Health Economics, 10 to 15 percent of adults report penicillin allergies, and prescribing an alternative for such patients is complicated by concern that the patient may have similar sensitivity to other antibiotics as well.
A recent report published by U.S. News & World Report Health states that most patients with penicillin allergies can be prescribed cephalosporins, especially if the allergy skin test results are negative. Cephalosporins resemble penicillin structurally and act by preventing the synthesis of the cell wall in the bacteria. More than 20 different cephalosporins are available and can be used to treat a variety of conditions, including infections of skin, urinary tract, respiratory tract and blood. Cephalosporins can be administered orally or intravenously, depending on the condition of the patient. Common side effects include nausea, vomiting and diarrhea.
Carbapenems, such as imipenem and meropenem, also have a structure similar to penicillin and act by preventing cell wall synthesis in the bacterial cell. Carbapenems were commonly avoided in patients with penicillin allergies due to the possibility of allergic reaction. However, in the October 2004 issue of the Journal of Antimicrobial Therapy, Dr. Manica Sodhi states that carbapenem use may be reasonable for patients with penicillin allergies, if caution is exercised. Carbapenems are effective against most pathogenic bacteria and are usually administered intravenously or intramuscularly. Common side effects include nausea, vomiting, rash and seizures.
Macrolides are a group of antibiotics that act by slowing the growth of the bacteria. According to Dr. A. Kruppa in the 1998 issue of Dermatology, these antibiotics, which include erythromycin, clarithromycin and azithromycin, are commonly used to treat patients with penicillin allergies because their spectrum of activity is very similar to that of penicillin and allergic reactions are rare. Macrolides can be taken orally or intravenously and diffuse well into all the body fluids except the cerebrospinal fluid. Mild gastric disturbances may occur.
A news report published in October 2000 by the American Society of Health-System Pharmacists states that although most hospital guidelines aim to limit the use of vancomycin to treat infections, most physicians prescribe vancomycin to all the patients who have penicillin allergies. Vancomycin can be administered orally or intravenously, depending on the condition of the patient. It acts by killing the bacteria. Common side effects include hearing loss, decreased urination and upset stomach.
Bactrim is a combination of two antibiotics, trimethoprim and sulfamethoxazole. It can be used to treat non-life-threatening infections in patients with penicillin allergies. Bactrim is available in tablet and liquid form and is taken orally with food two to four times a day. Common side effects include upset stomach, vomiting and loss of appetite