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Compare Cephalexin vs. Penicillin

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

Key takeaways

Cephalexin (Keflex) and penicillin V potassium (Penicillin VK) are both antibiotics used to treat bacterial infections, but they belong to different medication classes. Cephalexin is a cephalosporin antibiotic, while penicillin V potassium is a penicillin antibiotic. Both medications can treat respiratory and skin infections, but cephalexin is also used for urinary tract infections (UTIs) and bone infections, while penicillin V potassium is used for strep throat and to prevent rheumatic fever. Cephalexin is typically taken 2 to 4 times a day, whereas penicillin V potassium is taken 3 to 4 times a day. Cephalexin is available as a generic in capsules, tablets, and liquid forms, while penicillin V potassium is available as a generic in tablets and suspension. Common side effects for both include nausea, vomiting, and diarrhea, but cephalexin can also cause dizziness and fatigue. Cephalexin may interact with metformin and probenecid, while penicillin V potassium should not be taken with other antibiotics unless prescribed together. Both medications require a prescription and should be taken exactly as directed to avoid resistance and ensure effectiveness.

  • Cephalexin
    Penicillin v potassium (Penicillin VK)
  • Cephalexin
    Penicillin v potassium (Penicillin VK)

  • Summary of Cephalexin vs. Penicillin

    Summary for Cephalosporin antibiotic
    Prescription only

    Cephalexin is a common antibiotic that's used to treat many different bacterial infections including urinary tract infections (UTIs), ear infections, and sinus infections, to name a few. Cephalexin is a cephalosporin antibiotic that kills bacteria to fight the infection. It's safe to use in people over the age of 1, and it's typically taken by mouth 2 to 4 times per day. This medication is available as a lower-cost generic capsule, tablet, and suspension; the brand name Keflex is no longer available. Side effects can include nausea, vomiting, and diarrhea.

    Summary for Penicillin antibiotic
    Prescription only

    Penicillin V potassium (Penicillin VK) is an antibiotic used to treat several types of infections throughout the body in adults and children. It's available as tablets and suspension that are taken by mouth. The dosage depends on the type of infection you have and how severe it is, but the medication is typically taken every 6 to 12 hours. Side effects include nausea, diarrhea, and vomiting.

  • Indications of Cephalexin vs. Penicillin

    Indications for
    •Respiratory tract infections
    •Ear infections
    •Skin infections
    •Bone infections
    •Urinary tract infections (UTIs)
    •Reproductive system infections
    Indications for
    •Certain types of streptococcal infections, such as upper respiratory tract infections, strep throat, scarlet fever, erysipelas (a type of skin infection)
    •Pneumococcal respiratory tract infections
    •Staphylococcal skin infections
    •Vincent's gingivitis
    •Prevention of rheumatic fever or chorea (long-term problems from strep infection)
    •Prevention of heart valve infections in certain people with heart problems

  • Pros and Cons of Cephalexin vs. Penicillin

    Pros and Const for Cephalosporin antibiotic
    Pros
    •Treats several common types of bacterial infections
    •Can use for adults and children over the age of 1
    •Available as a liquid for people who have trouble swallowing pills
    •Available as a lower-cost generic
    Cons
    •Usually need to take a few times per day
    •Might not be able to take if you're allergic to penicillins or other cephalosporin antibiotics
    •Not recommended for the cold or flu (these are viral illnesses, not bacterial infections)
    Pros and Const for Penicillin antibiotic
    Pros
    •Works well to treat many different bacterial infections
    •Can use for adults and children
    •Can be taken with or without food
    •Available as a tablet and suspension
    Cons
    •Can cause stomach side effects like nausea, vomiting, and diarrhea
    •Might not be able to take this medication if you've had a severe allergy to penicillin
    •Not recommended for treating a cold or the flu because these are viral infections
    •Needs to be taken every 6 to 8 hours

  • Common Side Effects of Cephalexin vs. Penicillin

    Common Side Effects for
    •Diarrhea
    •Nausea
    •Vomiting
    •Indigestion
    •Stomach pain
    Common Side Effects for
    •Nausea
    •Vomiting
    •Stomach upset
    •Diarrhea

  • Warnings of Cephalexin vs. Penicillin

    Common Side Effects for
    •Allergic reactions
    •Diarrhea from Clostridioides difficile infection
    •Development of drug-resistant bacteria
    •Seizures
    •Higher risk of bleeding
    Common Side Effects for
    •Allergic reaction
    •Infectious diarrhea
    •Development of drug-resistant bacteria

  • Prices with our coupons for Cephalexin vs. Penicillin

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