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

When your doctor prescribes cephalexin, a first-generation cephalosporin antibiotic used to treat bacterial infections. Also known as Keflex, it’s one of the most commonly prescribed antibiotics for everyday infections like skin boils, strep throat, and urinary tract infections. Unlike some stronger antibiotics, cephalexin is usually the first line of defense — it’s effective, affordable, and has been around for decades. But knowing what it does — and what it doesn’t — can save you from side effects, missed doses, or even antibiotic resistance.

It works by attacking the cell walls of bacteria, making them burst and die. That’s why it’s useless against viruses like colds or flu. You’ll often see it paired with other treatments in posts about bacterial skin infections, a common reason people are prescribed cephalexin, or used after minor surgeries to prevent infection. It’s also a go-to for people who can’t take penicillin — though cross-reactivity is possible, so always tell your doctor about allergies. Many of the posts here cover how cephalexin fits into broader medication safety, like drug interactions, how other meds, supplements, or even food can mess with its effectiveness. Grapefruit juice? Usually fine. But antacids? They can block absorption if taken at the same time.

Side effects are usually mild — upset stomach, diarrhea, or a rash — but if you get severe diarrhea with blood or fever, stop taking it and call your doctor. That could be C. diff, a serious infection triggered by antibiotics wiping out good gut bacteria. And never save leftover cephalexin for next time. Incomplete courses are a big reason bacteria become resistant. The posts below show real cases: people using it for infected cuts, ear infections, or even dental abscesses. Others warn about mixing it with other drugs like blood thinners or diabetes meds. You’ll also find tips on how to take it right — with or without food, how long to wait before eating, and what to do if you miss a dose.

What’s clear from the collection is that cephalexin isn’t magic. It’s a tool — useful, but only when used correctly. Whether you’re treating a child’s ear infection or recovering from a minor surgery, understanding how it works, how it interacts with your body, and why timing matters can make all the difference. The posts ahead don’t just list facts — they show you how real people use it, what went right, what went wrong, and how to avoid the common mistakes.