Cephalexin: What it is and when it helps

Cephalexin is a commonly prescribed antibiotic used for many routine bacterial infections. You’ll see it for skin infections, middle ear infections, throat infections, and some urinary tract infections. It belongs to the first-generation cephalosporin family and works by stopping bacteria from building a cell wall, which kills them. That makes it effective for certain strains of staph and strep-type bacteria.

How to take cephalexin

Doctors usually prescribe cephalexin as a capsule or liquid. A typical adult dose is 250–500 mg every 6–12 hours depending on the infection. Kids get a weight-based dose—your doctor or pharmacist will tell you exactly how much. Take it with or without food. Try to take doses at regular intervals and finish the entire course even if you feel better early. If you miss a dose, take it as soon as you remember but skip it if the next dose is nearly due—don’t double up.

Storage is simple: keep the capsules or suspension at room temperature and away from direct sunlight. If you have the liquid form, follow the label for refrigeration instructions and throw away any unused medicine after the date given.

Side effects and safety tips

Most people tolerate cephalexin well. The common side effects are mild stomach upset, diarrhea, and occasional rash. If you get persistent, watery diarrhea or severe abdominal pain, call your doctor—this could be a sign of Clostridioides difficile infection, which needs medical care.

Allergic reactions can happen. If you develop hives, swelling of the face or throat, trouble breathing, or a fast heart rate, seek emergency care right away. If you’ve had a severe allergic reaction to penicillin in the past, tell your prescriber—there’s some chance of cross-reaction, though it’s lower than once thought.

Drug interactions are limited but real. Probenecid can raise cephalexin levels, so mention it if you take that medicine. Always list all prescription and over-the-counter drugs, and supplements, so your clinician can check for interactions.

Pregnant or breastfeeding? Cephalexin is commonly used in pregnancy, but you should still discuss risks and benefits with your provider. For breastfeeding, most experts say the drug is compatible, but confirm with your clinician.

One last practical point: don’t use antibiotics for viral illnesses like colds or most sore throats without a clear bacterial diagnosis. Misusing antibiotics drives resistance and makes future infections harder to treat. If symptoms worsen or don’t improve after a few days on cephalexin, call your doctor—your infection might need a different drug or further evaluation.