Penicillin VK

Medical Reviewer: John P. Cunha, DO, FACOEP Last updated on RxList: 7/6/2021
Penicillin VK Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Penicillin VK?

Penicillin V potassium (penicillin VK) is an antibiotic used to treat mild to moderately severe infections due to penicillin G-sensitive microorganisms. Penicillin VK is available in generic form.

What Are Side Effects of Penicillin VK?

Side effects of penicillin VK include:

  • nausea,
  • vomiting,
  • diarrhea,
  • abdominal pain,
  • stomach upset,
  • skin rash,
  • hives,
  • itching, and
  • black "hairy" tongue.

Patients with a history of allergic reactions to other penicillins should not receive penicillin VK. Serious but rare reactions to penicillin VK include:

  • seizures,
  • severe allergic reactions (anaphylaxis), and
  • low platelet or red blood cell count.

Penicillin VK can alter the normal bacteria in the colon and allow overgrowth of some bacteria such as Clostridium difficile, which causes inflammation of the colon (pseudomembranous colitis).

Dosage for Penicillin VK

The usual adult dose of penicillin VK is 125 to 500 mg every 6-8 hours.

What Drugs, Substances, or Supplements Interact with Penicillin VK?

Benemid (Probenecid) causes an increase in the level of penicillin VK in the blood by reducing the elimination of penicillin by the kidneys.

Penicillin VK During Pregnancy and Breastfeeding

Penicillin VK is considered safe during pregnancy. Penicillin VK is excreted in breast milk and may cause diarrhea or allergic responses in nursing infants.

Additional Information

Our Penicillin VK Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Penicillin VK Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • the first sign of any skin rash, no matter how mild;
  • red or scaly skin;
  • fever, chills, swollen glands, muscle or joint pain, fast heartbeats, general ill feeling;
  • a light-headed feeling, like you might pass out;
  • severe stomach pain, diarrhea that is watery or bloody;
  • little or no urinating;
  • bruising, severe tingling, numbness, pain, muscle weakness;
  • seizure (convulsions); or
  • unusual changes in mood or behavior.

Common side effects may include:

  • mild diarrhea;
  • headache;
  • black or hairy tongue; or
  • pain, swelling, bruising, or irritation around the IV needle.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Penicillin VK (Penicillin V Potassium)


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Penicillin VK Professional Information


Although the incidence of reactions to oral penicillins has been reported with much less frequency than following parenteral therapy, it should be remembered that all degrees of hypersensitivity, including fatal anaphylaxis, have been reported with oral penicillin.

The most common reactions to oral penicillin are nausea, vomiting, epigastric distress, diarrhea, and black hairy tongue. The hypersensitivity reactions reported are skin eruptions (maculopapular to exfoliative dermatitis), urticaria and other serum-sicknesslike reactions, laryngeal edema, and anaphylaxis.

Fever and eosinophilia may frequently be the only reaction observed. Hemolytic anemia, leukopenia, thrombocytopenia, neuropathy, and nephropathy are infrequent reactions and usually associated with high doses of parenteral penicillin.

Read the entire FDA prescribing information for Penicillin VK (Penicillin V Potassium)

© Penicillin VK Patient Information is supplied by Cerner Multum, Inc. and Penicillin VK Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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