What is cephalexin used for?

Cephalexin is a first‑generation cephalosporin antibiotic. It’s used to treat infections caused by susceptible bacteria, especially:

- Skin and soft tissue infections (e.g., cellulitis, impetigo)
- Ear infections (otitis media)
- Sinusitis and other upper respiratory infections
- Throat infections (pharyngitis/tonsillitis)
- Some urinary tract infections (uncomplicated)
- Some bone infections (osteomyelitis) in select cases

Important notes:
- It is not effective against MRSA or many resistant organisms.
- It works best against certain gram-positive bacteria (strep, non-MMRSA staph) and some gram-negative bacteria (like E. coli, Proteus, Klebsiella) but coverage is limited.
- People with a penicillin allergy may be at risk for cross-reactivity and should use cephalexin only under a clinician’s guidance.
- Common side effects: upset stomach, diarrhea. Seek care if you have severe allergic symptoms, severe diarrhea, or at-home treatment isn’t helping within a few days.

If you’re considering this for yourself or someone else, it’s best to use it only under a healthcare provider’s instructions.