Compare amoxicillin vs. Penicillin

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

Amoxil
(amoxicillin)

Penicillin Vk
(penicillin)

Treats bacterial infections. Amoxil (amoxicillin) is a good and cheap antibiotic that comes in different forms to treat many types of bacterial infections.Kills bacteria. Penicillin Vk (Penicillin) is good for treating many bacterial infections and is available as a generic. You may need to use another form of birth control along with your birth control pills. It's also best taken on an empty stomach but it can cause an upset stomach.
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Reviews & ratings
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5amoxicillin
Reviews for Amoxil (amoxicillin)
62%
of people (All ages) say Amoxil (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 Penicillin Vk (penicillin)
71%
+9% better vs. Amoxil (amoxicillin)
52%
+7% better vs. Amoxil (amoxicillin)
12%
+2% better vs. Amoxil (amoxicillin)
1297 reviews
Have you used Penicillin Vk (penicillin)?
Worth itNot sureNot worth it
Side effects
amoxicillinPenicillin

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

More about amoxicillin side effects »

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

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

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

      The FDA hasn’t classified this medicine’s effects on unborn babies. Talk with your doctor about this medicine if you’re pregnant or planning on it.

      Food
      amoxicillinPenicillin
      • Take with food to prevent upset stomach. If you're taking the extended-release version, take within 1 hour of finishing your meal.
      No food related info.
      Upsides and benefits
      amoxicillinPenicillin
      • 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.
      Downsides and risks
      amoxicillinPenicillin
      • 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.
      • Many bacteria have developed resistance. Your doctor may run tests to see if Penicillin will work on your infection.
      • Can make birth control pills less effective.
      • Best taken on an empty stomach, but can cause stomach upset and diarrhea.
      Tips from our pharmacists for people taking the medication
      amoxicillinPenicillin
      • 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
      • Take this medication exactly how your doctor tells you to.
      • If you're taking birth control pills, this medication can make them less effective.
      • Try to take it on an empty stomach. If this gives you an upset stomach, take it with food.
      • Can cause diarrhea, nausea or vomiting.
      Learn more
      More about amoxicillinSide effectsReviews & ratingsAlternativesFDA package insert
      Have you used Amoxil (amoxicillin)?
      Worth itNot sureNot worth it
      More about PenicillinSide effectsReviews & ratingsAlternativesFDA package insert
      Have you used Penicillin Vk (penicillin)?
      Worth itNot sureNot worth it