Keflex (Cephalexin): What It Treats, How to Use It, and Buying Tips

Keflex is a widely used antibiotic that treats everyday infections like skin infections, ear infections, throat infections, and some urinary tract infections. If a doctor prescribed Keflex, you probably want to know how it works, what to watch for, and whether it’s safe to buy online. Here’s clear, practical advice you can use right away.

Cephalexin (the active drug in Keflex) belongs to the cephalosporin family. It kills bacteria by damaging their cell walls so the bugs can’t survive. That means it only works on bacterial infections, not viruses like colds or the flu. Using it for the wrong reason won’t help and can cause resistance.

Who should take it and typical dosing

Doctors pick Keflex for common infections because itʼs reliable and well-known. Typical adult doses vary by infection: commonly 250–500 mg every 6–12 hours. For more serious infections a doctor may use higher doses. For kids the dose is weight-based—often around 25–50 mg per kg per day divided into multiple doses. Follow the exact prescription your provider gives you; don't guess.

Most courses run 5–14 days depending on the infection. If symptoms improve quickly, finish the full course unless your doctor tells you otherwise. Stopping early can let the infection come back stronger.

Side effects, warnings, and safe use

Common side effects are mild: stomach upset, nausea, diarrhea, or a rash. If you get severe diarrhea, especially with blood or fever, contact your doctor—this can be a sign of C. difficile, a serious gut infection linked to antibiotics.

If you have a penicillin allergy, tell your provider. Some people allergic to penicillin react to cephalosporins too. Signs of a dangerous allergic reaction include hives, swelling of the face or throat, and trouble breathing—call emergency services right away.

Kidney function affects dosing. If you have kidney disease, your doctor may lower the dose. Pregnant or breastfeeding? Most clinicians consider cephalexin safe, but you should still check with your provider.

Take Keflex with or without food. If you miss a dose, take it when you remember but don’t double up to catch up. Keep a record so you don’t miss doses and avoid resistance.

Thinking of buying Keflex online? Never buy antibiotics from sites that don’t ask for a prescription. Look for clearly listed contact info, licensed pharmacy credentials, and verified reviews. Very low prices or offshore sites that ship without prescriptions are risky—fake drugs can be ineffective or dangerous.

If you’re unsure whether Keflex is right for your problem, ask a clinician or pharmacist. They can confirm the diagnosis, pick the correct dose, and point you to safe ways to get your medication. Want more on antibiotics and safe online pharmacies? Check related guides on our site for practical tips and trusted sources.