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.
Find lowest prices
Powered by GoodRxSave on your next prescription. Be sure you’re getting the lowest price for your medication, even if you have insurance.
Coupons for Bactrim
Best available price for 20 (800mg/160mg) tablets of bactrim
Reviews & ratings
Filter group. All currently selected
Filter group. All currently selected
5.28Penicillin
Reviews for Penicillin
71%
of people (All ages) say 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
59%
+12% better vs. Penicillin
49%
+3% better vs. Penicillin
22%
+10% better vs. 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.
Type of medication
PenicillinBactrim
Prescription onlyPrescription 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 »
  • Elderly
  • Taking other medicines that lower kidney function
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.

Kidneys and liver
PenicillinBactrim
No kidneys and liver related info.
  • Bactrim (sulfamethoxazole / trimethoprim) can harm your kidneys, especially if you're taking anti-inflammatory pain relievers like Motrin or Advil or other medicines that also affect your kidneys. Make sure to drink plenty of water or fluids while you're taking Bactrim (sulfamethoxazole / trimethoprim).
Upsides and benefits
PenicillinBactrim
  • Available in generic.
  • Available in different forms: tablet, capsule and suspension.
  • Used to treat many types of bacterial infections.
  • Widely available as a generic product and in a variety of formulations (tablet, capsule, suspension).
  • Works well to treat many types of bacterial infections
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 you sensitive to the sun.
  • Can upset your stomach
  • Drink plenty of water or fluids to avoid harming your kidneys
  • May cause birth defects
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 Bactrim (sulfamethoxazole / trimethoprim) exactly the way your doctor tells you.
  • Can make you more sensitive to the sun. Keep out of the sun or wear protection while under the sun.
  • Drink plenty of water or liquids while on Bactrim (sulfamethoxazole / trimethoprim) to avoid harming your kidneys.
  • Can cause upset stomach.
  • Can cause an allergic reaction. Talk to your doctor if you notice skin rash or swelling of your face.
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