From the Research
If you are allergic to lisinopril, Keflex (cephalexin) is generally safe to take as these medications belong to completely different drug classes with different chemical structures. Lisinopril is an ACE inhibitor used for blood pressure and heart conditions, while Keflex is a cephalosporin antibiotic used to treat bacterial infections. The allergic reactions to lisinopril (which often include cough, angioedema, or skin rash) are specific to ACE inhibitors and do not predict allergic reactions to antibiotics like Keflex. However, if you have a history of severe allergic reactions to any cephalosporin antibiotics or penicillins, you should exercise caution with Keflex, as there is approximately 2% cross-reactivity between these antibiotic classes, as reported in a study published in JAMA in 2019 1. Some key points to consider when taking Keflex include:
- Informing your healthcare provider about all your allergies before starting any new medication
- Watching for signs of allergic reaction when taking Keflex for the first time, such as rash, itching, swelling, dizziness, or difficulty breathing
- Understanding that the incidence of new antibiotic allergy reports is minimally and non-specifically increased among individuals with a preexisting antibiotic allergy, as reported in a study published in The journal of allergy and clinical immunology in 2022 2 It's also important to note that many patients report allergies to β-lactam antibiotics that limit their use, resulting in the use of broad-spectrum antibiotics that increase the risk for antimicrobial resistance and adverse events, as reported in a study published in JAMA in 2019 1. Therefore, it's crucial to evaluate penicillin allergy before deciding not to use penicillin or other β-lactam antibiotics, and to identify patients who are at low risk for developing an allergic reaction to penicillin, as reported in a study published in JAMA in 2019 1.