Cephalexin: Uses, Dosage, Side Effects, and How to Buy Safely

Cephalexin (brand name Keflex) is a common oral antibiotic used for skin infections, ear infections, bronchitis, and some urinary tract infections. It’s a cephalosporin — similar in action to penicillin — and works by stopping bacteria from building their cell walls. That makes it useful for many routine bacterial infections, but not for viruses like colds or the flu.

How Cephalexin is used and typical doses

Adults usually take 250–500 mg every 6–12 hours, depending on the infection. For skin and soft tissue infections doctors often use 500 mg every 12 hours. For strep throat, 500 mg twice daily for 10 days is common. Children’s doses are weight-based — commonly 25–50 mg per kg per day divided into doses every 8–12 hours. Typical treatment length is 5–14 days depending on the infection and how quickly symptoms improve.

If you have reduced kidney function your doctor will lower the dose or stretch the dosing interval. Always follow the exact prescription and finish the full course even if you feel better early. Stopping early can let bacteria return stronger.

Side effects, allergies, and warnings

Most people tolerate cephalexin well. Common side effects are stomach upset, diarrhea, and mild rash. If you get severe diarrhea, especially with blood or mucus, tell your doctor — that can signal C. difficile infection, which needs immediate care.

If you’re allergic to penicillin, mention it to your provider. Cross-reactivity between penicillins and cephalosporins is possible but not automatic. If you’ve had hives, swelling, or anaphylaxis from penicillin, your clinician will likely choose a different antibiotic.

Watch for signs of a serious allergic reaction to cephalexin: difficulty breathing, facial swelling, or a fast-spreading rash. Stop the drug and seek emergency care if that happens. Also tell your doctor about liver or kidney problems, pregnancy, or breastfeeding — adjustments may be needed.

Drug interactions are limited but real. Probenecid can raise cephalexin levels. Antibiotics can alter gut bacteria and occasionally reduce the effectiveness of hormonal birth control; consider extra precautions if this concerns you. If you take multiple drugs, have your pharmacist check for interactions.

Thinking of buying cephalexin online? Buy only from licensed pharmacies that require a prescription. Good signs: a physical address, licensed pharmacist contact, clear prescription policy, and verified accreditation (look for NABP or national equivalents). Avoid sites that sell prescription meds without asking for a prescription or that offer suspiciously low prices.

When ordering online, confirm packaging, expiration dates, and secure checkout. If a site ships from another country, check local rules — some countries have different names and formulations. If in doubt, call a pharmacist or your doctor first.

Cephalexin is reliable for many common infections when used correctly. Ask questions, follow dose instructions, and contact your healthcare provider if side effects or symptoms don’t improve after a few days. Safe use keeps you healthier and helps antibiotics keep working for everyone.