Cefaclor: What It Is, How It Works, and What You Need to Know

When your doctor prescribes cefaclor, a second-generation cephalosporin antibiotic used to treat bacterial infections like ear infections, bronchitis, and skin infections. Also known as Cefaclor Monohydrate, it works by stopping bacteria from building their cell walls, which kills them or stops them from spreading. Unlike penicillin, cefaclor is often used when someone has a mild allergy to it—or when the infection doesn’t respond to first-line drugs. It’s not for viruses like colds or flu, but for confirmed bacterial cases where timing matters.

People often mix up cephalosporins, a family of antibiotics that includes cefaclor, cephalexin, and cefdinir. Also known as cephalosporin antibiotics, they’re grouped by generations based on how broad their coverage is. Cefaclor sits in the second generation, meaning it handles more types of bacteria than first-gen drugs like cephalexin, especially some that cause sinus and lung infections. But it’s not as strong as third-gen options like ceftriaxone, which are given in hospitals. If you’ve taken amoxicillin and it didn’t help, your doctor might switch you to cefaclor—not because it’s stronger, but because it works differently. Many patients wonder how it compares to other antibiotics like doxycycline, a tetracycline antibiotic used for acne, Lyme disease, and some respiratory infections. Also known as Vibramycin, it’s not a cephalosporin and works by stopping bacteria from making proteins instead of breaking their walls. That means if your infection is caused by something like chlamydia or a tick-borne bug, doxycycline might be better. But for a stubborn ear infection, cefaclor is often the go-to.

Cefaclor isn’t perfect. About 1 in 10 people report stomach upset, diarrhea, or nausea. Rarely, it can cause a serious allergic reaction—especially if you’ve had one to penicillin. That’s why doctors ask about your allergy history before prescribing it. It’s also not safe for everyone. People with kidney problems may need a lower dose. And unlike some antibiotics you take once a day, cefaclor usually requires two or three doses daily, which makes sticking to the schedule harder. But if you finish the full course, even if you feel better, you lower the risk of the infection coming back stronger.

What you’ll find in the posts below isn’t just a list of articles. It’s real-world guidance from people who’ve taken cefaclor and others who’ve dealt with similar infections. You’ll see how it stacks up against other antibiotics, what side effects actually happen, how to tell if it’s working, and when to call your doctor. Some posts compare it to drugs like minocycline or amoxicillin. Others explain how to avoid common mistakes—like skipping doses or mixing it with antacids. This isn’t theoretical. These are the questions patients ask, and the answers they need to stay safe and get better.