Cephalexin Comparison: How It Stacks Up Against Other Antibiotics

When you’re prescribed Cephalexin, a first-generation cephalosporin antibiotic used to treat bacterial infections like skin infections, urinary tract infections, and respiratory infections. Also known as Keflex, it’s one of the most commonly prescribed antibiotics for mild to moderate infections. But it’s not the only option—and knowing how it compares to others can help you understand why your doctor picked it, or if there’s a better fit for your situation.

Cephalexin works by breaking down the cell walls of bacteria, which stops them from multiplying. That’s similar to how amoxicillin, a penicillin-class antibiotic often used for ear infections, sinus infections, and strep throat works. But while amoxicillin covers a broader range of bacteria, cephalexin is often chosen when someone has a penicillin allergy—or when the infection is more likely to be caused by skin bacteria like Staphylococcus. It’s also cheaper than many newer antibiotics, which is why it shows up so often in prescriptions.

Compared to doxycycline, a tetracycline antibiotic used for acne, Lyme disease, and some respiratory infections, cephalexin doesn’t work as well against certain types of bacteria, especially those that cause tick-borne illnesses or severe acne. But doxycycline can cause sun sensitivity and upset stomach more often, while cephalexin tends to be gentler on the gut—though it still can cause diarrhea or nausea. Then there’s clindamycin, an antibiotic often used for skin abscesses or when other drugs fail. It’s stronger in some cases but carries a higher risk of serious diarrhea caused by C. diff. Cephalexin? Much lower risk there.

People often ask if cephalexin is better than amoxicillin. The answer? It depends. For a simple skin infection, cephalexin might be the go-to. For a child with an ear infection, amoxicillin is still the first-line choice. For someone allergic to penicillin, cephalexin is often a safe alternative—though not always. About 10% of people with penicillin allergies also react to cephalosporins like cephalexin. That’s why your doctor checks your history before prescribing.

Cost matters too. Generic cephalexin usually costs under $10 for a full course at most pharmacies. That’s cheaper than many branded antibiotics and even some generics like azithromycin. It’s also taken fewer times a day than some others—usually every 6 to 12 hours—which makes it easier to stick with.

Side effects? Most people tolerate it fine. The big ones are diarrhea, nausea, and occasional rash. Rarely, it can cause severe allergic reactions. If you’ve had a reaction to any antibiotic before, tell your doctor. And never save leftover cephalexin for next time—using antibiotics without a current diagnosis is how resistant bacteria spread.

What you’ll find below are real, side-by-side comparisons of cephalexin with other common antibiotics. No theory. No fluff. Just clear breakdowns of what works, what doesn’t, who it’s best for, and how the side effects stack up. Whether you’re comparing it to amoxicillin, doxycycline, clindamycin, or others, you’ll see exactly how they differ—and why one might be right for you while another isn’t.