Cefaclor vs Amoxicillin: Key Differences and When to Choose Each

When you're dealing with a bacterial infection, your doctor might prescribe either cefaclor, a second-generation cephalosporin antibiotic used for ear, skin, and respiratory infections. Also known as Cefaclor, it's often chosen when penicillin doesn't work or causes a reaction. or amoxicillin, a broad-spectrum penicillin antibiotic commonly used for sinus, throat, and urinary tract infections. Also known as Amoxil, it's one of the most prescribed antibiotics worldwide for its effectiveness and low cost. Both treat similar bugs, but they're not interchangeable—and picking the wrong one can mean a longer illness or worse side effects.

Amoxicillin works great against common bugs like strep throat and ear infections, especially in kids. It’s gentle on the stomach and usually taken three times a day. But if you’re allergic to penicillin, it’s off the table. That’s where cefaclor comes in. It’s not a penicillin, so it’s often safe for people with penicillin allergies—though not always. Cefaclor also handles some resistant strains better, like certain ear infections that don’t clear up with amoxicillin. It’s taken twice daily, which some people prefer, but it can cause more stomach upset and diarrhea than amoxicillin.

Doctors don’t just pick one because it’s newer or stronger. They look at what bug they’re fighting, your allergy history, past antibiotic use, and even how your body reacted before. For example, if you had a bad reaction to amoxicillin last time, cefaclor might be the next step. But if you’re treating a simple sinus infection and have no allergies, amoxicillin is still the go-to—it’s cheaper, widely available, and works just as well. Both are oral antibiotics, so you’ll take them at home, but neither works for viral infections like colds or flu. Using them when they’re not needed breeds resistant bacteria, which makes future infections harder to treat.

What you’ll find below are real comparisons from people who’ve used both—side effects they experienced, how quickly symptoms cleared, and why one worked when the other didn’t. You’ll see cases where cefaclor saved the day after amoxicillin failed, and others where amoxicillin was the clear winner. No fluff. No marketing. Just facts from real treatment experiences.