Keflex (cephalexin): what it treats and how to use it safely

Keflex is the brand name for cephalexin, a first‑generation cephalosporin antibiotic. Doctors commonly prescribe it for skin infections, strep throat, some ear infections, and certain urinary tract infections. If your doctor wrote Keflex for you, this page gives easy, useful info on doses, side effects, precautions, and how to find a good price without risking safety.

How Keflex works and when it’s used

Cephalexin kills bacteria by stopping them from building cell walls. That makes it good for common Gram‑positive bugs like Staph and Strep and for some Gram‑negative bugs too. Typical uses include: uncomplicated skin infections (boils, cellulitis), strep throat when penicillin can’t be used, and simple UTIs. It won’t work for viral infections like colds or most coughs—so don’t ask your prescriber for it unless there’s a clear bacterial reason.

Most courses last 5–10 days depending on the infection. Always follow your prescriber’s plan—stopping early can let the infection come back and breed resistance.

Dosage, side effects, and safety tips

Adult doses commonly range from 250 mg to 500 mg every 6–12 hours. For more serious infections the dose can be higher. Kids get weight‑based dosing—your pediatrician will tell you exactly what to give. Never improvise from household advice or old prescriptions.

Common side effects are stomach upset, diarrhea, and mild rash. If you develop hives, facial swelling, breathing trouble, or a severe rash—seek emergency care; those are signs of a serious allergic reaction. Also watch for severe, persistent diarrhea; antibiotics can cause C. difficile, which needs prompt treatment.

If you’re allergic to penicillin, tell your doctor. Some people who react to penicillin also react to cephalosporins, though cross‑reaction is less common than once thought. Mention other meds you take—cephalexin can interact with blood thinners like warfarin and affect gut flora when taken with probiotics or other antibiotics.

Store Keflex at room temperature, away from heat and moisture. Keep out of reach of children. Finish the full course unless your prescriber says otherwise.

Looking to save money? Compare local pharmacy prices and certified online Canadian pharmacies. Avoid sites that don’t require a prescription or that look unverified. Our site has a cephalexin price guide and tips to spot legit online pharmacies—check that if cost is the issue.

If you’re unsure whether Keflex is right for you, ask a healthcare provider. Bring up allergies, pregnancy or breastfeeding, and any other health problems. With the right use, Keflex is a simple, effective option for many common bacterial infections.