Key takeaways
Cephalexin (Keflex) and Amoxicillin (Amoxil) are both antibiotics used to treat bacterial infections, such as urinary tract infections (UTIs) and ear infections. However, they belong to different medication classes. Cephalexin is a cephalosporin antibiotic, while Amoxicillin is a penicillin antibiotic. Cephalexin is available as capsules, tablets, and liquid suspensions, and is typically taken 2 to 4 times a day. Amoxicillin comes in tablets, capsules, chewable tablets, and liquid forms, and is usually taken 2 to 3 times a day. Both medications are available as lower-cost generics. Common side effects for both include nausea, vomiting, and diarrhea, but Amoxicillin can also cause a rash. Cephalexin may interact with metformin, probenecid and warfarin while Amoxicillin can interact with probenacid, warfarin and allopurinol. If you have a penicillin allergy, you might also be allergic to Amoxicillin, but the risk is lower with Cephalexin.
