Compare Penicillin vs. Bactrim

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

Penicillin Vk
(Penicillin)

Bactrim
(Sulfamethoxazole / Trimethoprim)

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.Kills bacteria. Bactrim (Sulfamethoxazole / Trimethoprim) is good for treating many bacterial infections and is available as a generic. However, you can be more likely to sunburn. Also, it can cause birth defects, so talk to your doctor if you're pregnant.
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Reviews & ratings
Filter group. All currently selected
Filter group. All currently selected
5.28Penicillin
Reviews for Penicillin Vk (Penicillin)
71%
of people (All ages) say Penicillin Vk (Penicillin) is worth it
52%
say it works well
12%
say it's a big hassle
1297 reviews
Have you used Penicillin Vk (Penicillin)?
Worth itNot sureNot worth it
Reviews for Bactrim (Sulfamethoxazole / Trimethoprim)
59%
-12% worse vs. Penicillin Vk (Penicillin)
49%
-3% worse vs. Penicillin Vk (Penicillin)
22%
-10% worse vs. Penicillin Vk (Penicillin)
473 reviews
Have you used Bactrim (Sulfamethoxazole / Trimethoprim)?
Worth itNot sureNot worth it
Side effects
PenicillinBactrim

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

More about Penicillin side effects »

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

More about Bactrim side effects »
How it works
PenicillinBactrim
Penicillin Vk (Penicillin) is an antibiotic. It kills bacteria by preventing them from making their own protective covering.Bactrim (Sulfamethoxazole / Trimethoprim) is a combination antibiotic that contains sulfamethoxazole and trimethoprim. It kills bacteria by preventing them from making proteins and other chemicals that keep them alive.
Type of medication
PenicillinBactrim
Prescription only
Prescription only
Available as
PenicillinBactrim
  • Pill
  • Pill
  • Liquid
Used for
PenicillinBactrim
Risk factors for serious side effects
PenicillinBactrim
      • Prior severe allergic reaction to Penicillin Vk (Penicillin)
      Detailed Penicillin Vk (Penicillin) risks & warnings »
              Detailed Bactrim (Sulfamethoxazole / Trimethoprim) risks & warnings »
              Pregnancy

              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.

              Research studies with real people found harmful effects on unborn babies, but the benefits might outweigh the risks even if you’re pregnant. Talk with your doctor.

              Upsides and benefits
              PenicillinBactrim
              • Available in generic.
              • Available in different forms: tablet, capsule and suspension.
              • Used to treat many types of bacterial infections.
              • Available in generic.
              • Available in different forms: tablet, capsule and suspension.
              • Used to treat many types of bacterial infections.
              • Less resistance seen to this antibiotic. Your doctor may run tests to see if Bactrim responds to your infection.
              Downsides and risks
              PenicillinBactrim
              • 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.
              • Makes your skin more sensitive to the sun.
              • Has to be taken with plenty of liquids.
              • May cause birth defects.
              • Can cause diarrhea.
              Tips from our pharmacists for people taking the medication
              PenicillinBactrim
              • 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.
              • Take this medication exactly how your doctor tells you to.
              • Can make your skin more sensitive to the sun.
              • Drink plenty of liquids when taking the medication.
              • Can cause diarrhea, nausea or vomiting.
              • Can cause rash.
              Learn more
              More about PenicillinSide effectsReviews & ratingsAlternativesFDA package insert
              Have you used Penicillin Vk (Penicillin)?
              Worth itNot sureNot worth it
              More about BactrimSide effectsReviews & ratingsAlternativesFDA package insert
              Have you used Bactrim (Sulfamethoxazole / Trimethoprim)?
              Worth itNot sureNot worth it