The penicillin family of antibiotics and their chemically related cousins, the cephalosporins, remain the best treatment options for many serious infections including meniningitis and endocarditis (infection of a heart valve).
If a patient can’t take penicillin because of a severe allergic reaction, then other antibiotics can be used, but these alternatives may not be as effective in clearing the up infection as quickly as a pencillin-type drug.
Today, I was asked to give advice about a patient with a penicllin allergy who had developed pneumonia. This is a very common scenario and my first question in these situations is to ask “What form does the allergy take?” The usual answer is “I don’t know. It just says that the patient is penicillin allergic in the case notes”. I then ask the doctor to ask the patient. Often the patient will tell the doctor that penicillin makes them feel sick or dizzy or gives them a headache. These are possible side effects of the antibiotic but are not symptoms of an allergy, although patients often think they are. Mild side effects can be treated, for example by anti-nausea medication, allowing the patient to have the best drug for their infection.
Sometimes, it is not possible to ask the patient about the nature of their penicillin allergy because they are unconscious or very confused and unable to answer questions and, unless relatives or friends are on hand to give further information, alternatives to penicillin have to be used.
Recently, I was asked to see a patient who needed treatment for cellulitis (a skin infection) who was reportedly penicllin allergic. The patient had Alzheimer’s disease and was unable to tell me anything about the allergy. A quick look in her case notes told me that she had had courses of amoxicillin ( a penicillin-type antibiotic) and cefuroxime (a cephalosporin, closely related to penicillin) in the past without any ill effects. I recommended that she have a course of pencillin (which she completed without any sign of an alllergic reaction). The cellulitis was cured - and so was her “penicillin allergy”.
