Keflex (Cephalexin) – What It Is, How to Take It, and What to Watch For

Keflex is the brand name for the antibiotic cephalexin. Doctors prescribe it for skin infections, ear infections, throat infections, and urinary tract infections. It belongs to the cephalosporin class, which works by stopping bacteria from building their cell walls. If you’ve been given Keflex, you’re probably dealing with a bacterial infection that needs a short, effective treatment.

Typical Dosage and How to Use Keflex

The usual adult dose is 250 mg to 500 mg taken every 6‑8 hours. For more serious infections, doctors may increase it to 1 g every 6 hours. Kids get a dose based on weight, often 25‑50 mg per kilogram per day divided into three doses. Always swallow the tablet with a full glass of water and try to take it at the same times each day. If you miss a dose, take it as soon as you remember—unless it’s almost time for the next one. In that case, skip the missed dose; don’t double up.

Common Side Effects and When to Call a Doctor

Most people tolerate Keflex well. The most frequent complaints are mild stomach upset, diarrhea, or a brief rash. If diarrhea becomes watery, bloody, or lasts more than a few days, it could be a sign of C. difficile infection—call your doctor right away. Severe rash, swelling of the face, or trouble breathing means an allergic reaction and needs emergency care.

Other side effects to keep an eye on include headache, dizziness, or unusual tiredness. These are usually short‑lived, but if they persist, let your clinician know.

Because Keflex is cleared by the kidneys, people with kidney problems may need a lower dose. Tell your doctor about any kidney disease, pregnancy, or breastfeeding before starting the medication.

Drug interactions are relatively few, but antacids containing aluminum or magnesium can reduce the amount of Keflex your body absorbs. Take Keflex at least two hours before or after an antacid to avoid this issue.

Finish the entire prescription even if you start feeling better before it’s done. Stopping early can let the infection come back and may promote antibiotic resistance.

In summary, Keflex is a reliable, once‑or‑twice‑daily antibiotic for many common infections. Follow the dosing schedule, watch for the listed side effects, and keep your doctor informed of any health changes. When used correctly, it clears up infections quickly and safely.