Compare penicillin vs. Keflex

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

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Keflex (cephalexin)

Prescription only
Treats bacterial infections.

Penicillin VK (penicillin) is good at treating strep throat and is cheap, however, it can only be used for certain infections as many bacteria have developed resistance to it.

3.9/ 5 average rating with 1297 reviewsforpenicillin
Treats bacterial infections.

Keflex (cephalexin) is good for treating many bacterial infections, and is available as a generic.

3.7/ 5 average rating with 686 reviewsforKeflex
Upsides
  • Compared to alternatives, Penicillin VK (penicillin) is the preferred choice for treating strep throat infections.
  • This medicine is available as a generic, which is cheap.
  • It’s also available in different forms: pill and liquid.
  • 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
  • Many bacteria are resistant to Penicillin VK (penicillin), so it only works for certain infection typically in ear, nose, and throat.
  • Penicillin VK (penicillin) has a bitter taste. Children might not like the taste.
  • 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.
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Used for
Dosage forms
  • Pill
  • Liquid
  • Pill
  • Liquid
Price
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Reviews
1297 reviews so far
71%
saidit'sworth it
52%
saiditworked well
12%
saidit'sa big hassle

Have you used Penicillin VK (penicillin)?

Leave a review
686 reviews so far
64%
saidit'sworth it
48%
saiditworked well
14%
saidit'sa big hassle

Have you used Keflex (cephalexin)?

Leave a review
Side effects
The Penicillin VK (penicillin) FDA package insert doesn’t have numbers about how common side effects are.
The Keflex (cephalexin) FDA package insert doesn’t have numbers about how common side effects are.
Risks and risk factors
  • Diarrhea
    • Taking Penicillin VK (penicillin) for a long time
  • Interaction with birth control pills
  • Allergic reaction
    • History of severe allergic reaction to Penicillin VK (penicillin)
    • Cephalosporin medication allergy
See more detailed risks and warnings
  • Diarrhea
  • New infections while taking Keflex (cephalexin)
    • Weakened immune system
    • Not taking Keflex (cephalexin) correctly
  • Allergic reaction
    • History of penicillin or cephalosporin allergies
See more detailed risks and warnings