Compare amoxicillin vs. Keflex

Head-to-head comparisons of medication uses, side effects, ratings, and more.

Amoxil
(amoxicillin)

Keflex
(cephalexin)

Treats bacterial infections. Amoxil (amoxicillin) is a good and cheap antibiotic that comes in different forms to treat many types of bacterial infections.Treats bacterial infections. Keflex (cephalexin) is good for treating many bacterial infections, and is available as a generic.
Reviews & ratings
Filter group. All currently selected
Filter group. All currently selected
5amoxicillin
Reviews for amoxicillin
62%
of people (All ages) say amoxicillin is worth it
45%
say it works well
14%
say it's a big hassle
786 reviews
Have you used Amoxil (amoxicillin)?
Worth itNot sureNot worth it
Reviews for Keflex
64%
-2% worse vs. amoxicillin
48%
-3% worse vs. amoxicillin
14%
Same vs. amoxicillin
686 reviews
Have you used Keflex (cephalexin)?
Worth itNot sureNot worth it
Side effects
amoxicillinKeflex

The amoxicillin FDA package insert doesn’t have numbers about how common side effects are.

More about amoxicillin side effects »

The Keflex FDA package insert doesn’t have numbers about how common side effects are.

More about Keflex side effects »
How it works
amoxicillinKeflex
Amoxil (amoxicillin) is an antibiotic. It kills bacteria, and prevents them from reproducing and making their own protective covering.Keflex (cephalexin) is an antibiotic. It kills bacteria by preventing them from making their own protective covering.
Type of medication
amoxicillinKeflex
Prescription onlyPrescription only
Available as
amoxicillinKeflex
  • Pill
  • Chewable tablet
  • Extended-release tablet
  • Liquid
  • Pill
  • Liquid
Used for
amoxicillinKeflex
Risk factors for serious side effects
amoxicillinKeflex
  • Taking Amoxil (amoxicillin) for a long time
  • Weakened immune system
  • Not taking Amoxil (amoxicillin) correctly
  • History of penicillin allergies
  • Using oral birth control pills
Detailed Amoxil (amoxicillin) risks & warnings »
  • Weakened immune system
  • Not taking Keflex (cephalexin) correctly
  • History of penicillin or cephalosporin allergies
Detailed Keflex (cephalexin) risks & warnings »
Pregnancy

Research studies with animals haven’t found a risk to unborn babies, but it hasn’t been properly studied in humans.

Research studies with animals haven’t found a risk to unborn babies, but it hasn’t been properly studied in humans.

Food
amoxicillinKeflex
  • Take with food to prevent upset stomach. If you're taking the extended-release version, take within 1 hour of finishing your meal.
  • Can take with or without food.
  • Can be taken with or without food.
Upsides and benefits
amoxicillinKeflex
  • First choice medicine to treat many bacterial infections.
  • Available in generic.
  • Available in different forms: tablet, capsule, and liquid. The liquid comes in many different flavors to make it taste better for people who don't like pills.
  • Side effects are generally not too bad compared to other antibiotics.
  • Available in generic.
  • Available in different forms: tablet, capsule, and suspension.
  • Used to treat many types of bacterial infections.
  • Can be taken with or without food.
  • Generally few side effects compared with other antibiotics.
Downsides and risks
amoxicillinKeflex
  • While Amoxil (amoxicillin) can be used to treat different bacterial infections, many don't respond to it.
  • Can cause diarrhea, nausea, and vomiting.
  • Except for the extended-release form, you have to take Amoxil (amoxicillin) 2 to 3 times a day, which can be hard to remember.
  • The extended-release form can be more expensive because it's a brand name.
  • Can cause diarrhea.
  • You may need to take Keflex (cephalexin) 2 to 4 times a day, which can be hard to remember.
  • If you're allergic to penicillins or other antibiotics, you might not be able to take this medicine.
Tips from our pharmacists for people taking the medication
amoxicillinKeflex
  • Finish all of the medicine, even if you start to feel better. Stopping Amoxil (amoxicillin) early can make the infection come back and harder to treat.
  • If you're on birth control, Amoxil (amoxicillin) might make it less effective. Talk to your doctor to see if you need to use backup.
  • Take with food to prevent upset stomach. If you're taking the extended-release version, take within 1 hour of finishing your meal.
  • If you have the liquid, keep the bottle in the fridge. The bottle is only good for 14 days after you pick it up. Shake the bottle well before using each dose.
  • You may have diarrhea or stomach upset when taking Amoxil (amoxicillin), but it should get better soon after you've finished. If the diarrhea gets worse, tell your doctor
  • Finish all of the medicine your doctor gives you, even if you start to feel better. Stopping it early can cause the bacteria to develop resistance.
  • Store the suspension in the refrigerator. Shake well before using, and discard the bottle after 14 days.
  • Can take with or without food.
Learn more
More about amoxicillinSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Amoxil (amoxicillin)?
Worth itNot sureNot worth it
More about KeflexSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Keflex (cephalexin)?
Worth itNot sureNot worth it