Cephalexin (Keflex): Fast Facts and Practical Tips
Cephalexin is a go-to oral antibiotic for common infections — skin, throat, ear, and some urinary tract infections. It’s the kind of prescription doctors write often because it works and is easy to take. But like any antibiotic, it’s not a cure-all. Use it the right way and you’ll get the benefit while avoiding problems like resistance or unnecessary side effects.
How cephalexin is used and typical dosing
Doctors prescribe cephalexin in tablet or liquid form. For many adult infections, common doses are 250–500 mg every 6–12 hours depending on the infection and severity. Children’s doses are weight-based, so follow the label or your pharmacist’s instructions exactly. Finish the full course even if you feel better after a few days — stopping early can let bacteria come back stronger.
If you have kidney problems, your doctor may lower the dose. Don’t change dosing on your own. If you miss a dose, take it as soon as you remember unless it’s almost time for the next one; don’t double up.
Side effects, allergies, and drug interactions
Most people tolerate cephalexin well. Common side effects are stomach upset, diarrhea, and mild rash. Stop and call a doctor immediately if you get severe allergic reactions like hives, swelling, trouble breathing, or a widespread blistering rash. If you’ve had a true penicillin allergy, tell your provider — some people allergic to penicillin also react to cephalosporins, though not everyone does.
Cephalexin has few major drug interactions, but always tell your clinician about other medicines, especially blood thinners or probiotics you’re taking. If diarrhea is severe or bloody, see a doctor — that could signal C. difficile infection, which needs treatment.
Looking for alternatives? If cephalexin isn’t suitable, options include other cephalosporins or different antibiotic classes depending on the bug and your allergies. For skin infections, some clinicians use doxycycline or clindamycin; for urinary infections, nitrofurantoin or trimethoprim-sulfamethoxazole may be options. Your prescriber will pick the right drug based on culture results, local resistance patterns, and your medical history.
Thinking of buying cephalexin online? Use caution. Only buy from licensed pharmacies that require a prescription and show clear contact info and credentials. Several site reviews on our blog cover how to spot safe versus risky online drugstores — check them before you order.
Bottom line: cephalexin is effective for many common infections when used correctly. Ask your doctor or pharmacist if you’re unsure about dose, side effects, or whether an alternative would work better. If symptoms don’t improve within 48–72 hours, get medical advice — infections sometimes need a different antibiotic or further testing.
