Cephalexin: what it treats and how to use it safely

Need a simple, effective antibiotic for common bacterial infections? Cephalexin is a first-generation cephalosporin doctors often choose for skin infections, ear infections, simple respiratory infections, and some urinary tract infections. It works by stopping bacteria from building their cell walls, so the infection clears up as your immune system finishes the job.

Cephalexin usually comes as 250 mg or 500 mg capsules and as a liquid for kids. Your doctor picks the dose based on the infection and your weight. A common adult dose is 250–500 mg every 6–12 hours for 7–14 days, but don’t guess—follow the prescription. Stopping early can let the infection come back and breed resistant bacteria.

How to take cephalexin and avoid problems

Take cephalexin with a full glass of water. Food doesn’t change how well it works, but taking it with food can reduce stomach upset. If you forget a dose, take it as soon as you remember unless it’s almost time for the next one—don’t double up.

Watch for common side effects: nausea, diarrhea, and mild stomach cramps are the most frequent. A rash can also show up—if you get hives, swelling, or trouble breathing, get emergency care. If diarrhea is severe or bloody, contact your provider; that could be a sign of Clostridioides difficile overgrowth.

If you have kidney problems, your doctor may lower the dose. Tell your prescriber about all meds you take—probenecid can raise cephalexin levels, and there’s a small chance of interaction with blood thinners. Also mention any allergies: if you’ve had a serious reaction to penicillin, there’s a modest cross‑reactivity risk with cephalosporins, so your clinician will decide whether it’s safe.

Buying cephalexin and practical tips

You’ll usually need a prescription. When buying online, use a licensed pharmacy that asks for a prescription and shows clear contact info. Compare prices—digital apps and discount tools can save money at checkout. Keep the medicine in a cool, dry place and finish the full course unless your doctor says otherwise.

Pregnant or breastfeeding? Tell your doctor—cephalexin is commonly used in pregnancy but your provider will weigh benefits and risks. For children, use the liquid form and follow the weight-based dosing your pediatrician gives.

Want a quick checklist before you start cephalexin? 1) Confirm it’s for a bacterial infection, not a virus. 2) Share allergies and kidney history. 3) Get clear dosing instructions and how long to take it. 4) Know the common side effects and when to seek help. Simple steps make the treatment safer and more effective.

If you’re unsure whether cephalexin is right for you, ask your doctor or pharmacist—getting the right antibiotic at the right dose is the fastest way to feel better and avoid complications.