Yes, Keflex and cephalexin are the same medication. Keflex is the brand name, and cephalexin is the generic name. They contain the identical active ingredient, a first-generation cephalosporin antibiotic, and work the same way in your body.
Brand Name vs. Generic Name
Keflex is simply the trademarked label that the original manufacturer gave to cephalexin. The FDA-approved label states it directly: “Keflex Capsules (Cephalexin, USP).” When your prescription says cephalexin, your pharmacist can dispense either the brand-name Keflex or any FDA-approved generic version. The chemical compound is identical regardless of what’s printed on the bottle.
To be sold as a generic, a manufacturer must prove its product is bioequivalent to the brand-name drug. The FDA requires a single-dose crossover study comparing the generic tablet to the Keflex reference standard, measuring how much drug reaches the bloodstream and how quickly. If the results fall within strict confidence intervals, the generic is approved. This means switching between Keflex and generic cephalexin should produce no difference in effectiveness or safety.
Why You Might See Different Names at the Pharmacy
Most pharmacies automatically fill prescriptions with the generic version unless a doctor specifically writes “brand name only” or your state’s laws require otherwise. The generic is typically much cheaper. Retail pricing for generic cephalexin runs around $49 for a course, though discount programs can drop that significantly. Brand-name Keflex costs more, and the price gap widens without insurance. If your prescription label says “cephalexin” but your doctor mentioned “Keflex,” there’s no need to worry. You’re getting the same drug.
What Cephalexin Treats
Cephalexin works by breaking into bacterial cells and permanently disabling the proteins bacteria need to build their protective cell walls. Without intact walls, the bacteria die. It’s effective against a range of common infections:
- Skin infections like cellulitis and wound infections caused by staph and strep bacteria
- Respiratory tract infections including some types of pneumonia and strep throat
- Ear infections (otitis media), particularly in children
- Urinary tract infections caused by E. coli and related bacteria
- Bone infections caused by susceptible bacteria
It’s one of the most commonly prescribed oral antibiotics, partly because it’s been around for decades and has a well-understood safety profile. Keflex capsules come in 250 mg, 333 mg, 500 mg, and 750 mg strengths. Generic cephalexin is also available as an oral liquid suspension, which is useful for children or anyone who has difficulty swallowing capsules.
Allergy Considerations
Cephalexin belongs to the cephalosporin family of antibiotics, which is chemically related to penicillin. If you have a penicillin allergy, there’s a small chance of cross-reactivity. For first-generation cephalosporins like cephalexin, that risk falls in the range of 1% to 8%, according to CDC data. This is higher than the cross-reactivity seen with newer cephalosporins (under 1%). If you’ve had a serious allergic reaction to penicillin, such as hives, throat swelling, or anaphylaxis, make sure your prescriber knows before you take cephalexin.
One Limitation Worth Knowing
Some bacteria have developed the ability to produce enzymes that break down cephalexin before it can work. These resistant strains are becoming more common, which is one reason your doctor may choose a different antibiotic depending on your infection. Cephalexin remains highly effective for the conditions it’s designed to treat, but it won’t work against every type of bacteria. If your symptoms aren’t improving after a few days on the medication, that’s worth a follow-up conversation with your prescriber.