Cefalexin

Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections. It kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cefalexin is a β-lactam antibiotic within the class of first-generation cephalosporins. It works similarly to other agents within this class, including intravenous cefazolin, but can be taken by mouth. Cefalexin can treat certain bacterial infections, including those of the middle ear, bone and joint, skin, and urinary tract. It may also be used for certain types of pneumonia and strep throat and to prevent bacterial endocarditis. Cefalexin is not effective against infections caused by methicillin-resistant Staphylococcus aureus (MRSA), most Enterococcus, or Pseudomonas. Like other antibiotics, cefalexin cannot treat viral infections, such as the flu, common cold or acute bronchitis. Cefalexin can be used in those who have mild or moderate allergies to penicillin. However, it is not recommended in those with severe penicillin allergies. Common side effects include stomach upset and diarrhea. Allergic reactions or infections with Clostridioides difficile, a cause of diarrhea, are also possible. Use during pregnancy or breastfeeding does not appear to be harmful to the fetus. It can be used in children and those over 65 years of age. Those with kidney problems may require a decrease in dose. Cefalexin was developed in 1967. It was first marketed in 1969 under the brand name Keflex. It is available as a generic medication. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 86th most commonly prescribed medication in the United States, with more than 7 million prescriptions. In Canada, it was the fifth most common antibiotic used in 2013. In Australia, it was one of the top 10 most prescribed medications between 2017 and 2023.