Cephalexin: What It Is, How It Works, and What Alternatives You Should Know

When you’re prescribed an antibiotic for a stubborn infection, Cephalexin, a first-generation cephalosporin antibiotic used to treat bacterial infections like skin boils, strep throat, and urinary tract infections. Also known as Keflex, it’s one of the most commonly prescribed oral antibiotics in Canada and the U.S. because it’s effective, affordable, and generally well-tolerated. Unlike broad-spectrum drugs that hit everything, Cephalexin targets specific bacteria—mostly Gram-positive ones like Staphylococcus and Streptococcus—making it a go-to for everyday infections that don’t need heavy artillery.

It’s part of the beta-lactam antibiotics, a class of drugs that includes penicillins and other cephalosporins that work by breaking down bacterial cell walls. That’s why if you’re allergic to penicillin, your doctor might still consider Cephalexin—but only after checking your specific allergy history. Not everyone with a penicillin allergy reacts to cephalosporins, but the risk isn’t zero. It’s also used in kids and pregnant women when needed, which speaks to its safety profile when used correctly.

But Cephalexin isn’t the only option. If it doesn’t work—or if you develop side effects like nausea or diarrhea—your doctor might switch you to another antibiotic. Cefaclor, a second-generation cephalosporin with a broader range of coverage, is often compared to Cephalexin in clinical settings. Then there’s azithromycin, a macrolide antibiotic used for respiratory and skin infections, which works differently and can be better for patients who can’t take beta-lactams. And if you’re dealing with something more resistant, like a stubborn UTI or MRSA, clindamycin or other alternatives might be the next step. Each has its own strengths, side effects, and best-use cases.

What you’ll find in the posts below isn’t just a list of drug names. It’s real-world guidance on how these antibiotics compare, when they’re actually needed, how to avoid common mistakes, and how to spot if something’s gone wrong. You’ll see how Cephalexin stacks up against similar drugs, what to eat (or avoid) while taking it, and why some people get side effects while others don’t. There’s also advice on buying generic versions safely online—because cost matters, and not every pharmacy is trustworthy.

Whether you’re taking Cephalexin right now, were prescribed it and are wondering what else is out there, or just want to understand why your doctor chose it over another drug—this collection gives you the straight facts. No fluff. No marketing. Just what you need to know to make sense of your treatment and ask the right questions.