Ketoconazole: Uses, Dosage, Side Effects, and Interactions



Description and Pharmacology

Ketoconazole is an imidazole antifungal agent used in the prevention and treatment of a variety of fungal infections. It functions by preventing the synthesis of ergosterol, the fungal equivalent of cholesterol, thereby increasing membrane fluidity and preventing growth of the fungus.

Indications and uses

Ketoconazole tablets are not indicated for treatment of onychomycosis, cutaneous dermatophyte infections, or Candida infections.

Ketoconazole tablets should be used only when other effective antifungal therapy is not available or tolerated and the potential benefits are considered to outweigh the potential risks.

Ketoconazole tablets are indicated for the treatment of the following systemic fungal infections in patients who have failed or who are intolerant to other therapies: blastomycosis, coccidioidomycosis, histoplasmosis, chromomycosis, and paracoccidioidomycosis. Ketoconazole tablets should not be used for fungal meningitis because it penetrates poorly into the cerebrospinal fluid.


Ketoconazole should not be used in patients with a known hypersensitivity to ketoconazole.


There should be laboratory as well as clinical documentation of infection prior to starting ketoconazole therapy. The usual duration of therapy for systemic infection is 6 months. Treatment should be continued until active fungal infection has subsided.


The recommended starting dose of ketoconazole Tablets is a single daily administration of 200 mg (one tablet). If clinical responsiveness is insufficient within the expected time, the dose of Ketoconazole Tablets may be increased to 400 mg (two tablets) once daily.


In small numbers of children over 2 years of age, a single daily dose of 3.3 to 6.6 mg/kg has been used. Ketoconazole Tablets have not been studied in children under 2 years of age

Side Effects:

Some side effects of Ketoconazole which occur rarely include the following:

  • Itching
  • Rash
  • Headache
  • Nausea and vomiting

Adverse Reactions:

The risk of developing hepatitis may increase in relation to duration of Ketoconazole tablet treatment. This is because Ketoconazole is hepatotoxic.

Use in Pregnancy:

Ketoconazole should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus.

Use for Nursing Mothers:

Since ketoconazole is probably excreted in the milk, mothers who are under treatment should not breast feed.

Drugs interaction:

  1. Gastric acid suppressants (e.g., antacids, histamine H2-blockers, proton pump inhibitors) have been shown to reduce plasma concentrations of ketoconazole.
  2. Ketoconazole is a substrate and potent inhibitor of CYP3A4. Therefore, drug interactions may occur when it is co-administered with other drugs that interact with CYP3A4. Inducers of CYP3A4 may decrease the plasma concentrations of ketoconazole while inhibitors of CYP3A4 may do the opposite.
  • Antacids, cimetidine, ranitidine, rifampicin: decrease effectiveness of Ketoconazole.
  • Cyclosporine: increases blood cyclosporine levels.
  • Concomitant alcohol intake causes acute facial flushing and nausea. None has been reported on local application.

FDA Warning

The U.S. Food and Drug Administration (FDA) is warning health care professionals to avoid prescribing the antifungal medicine ketoconazole oral tablets to treat skin and nail fungal infections. Use of this medication carries the risk of serious liver damage, adrenal gland problems, and harmful interactions with other medicines that outweigh its benefit in treating these conditions, which are not approved uses of the drug.

Storage Conditions

Store below 25°C. Protect from moisture & light.

Ketoconazole Chemical Structure

Ketoconazole Chemical Structure



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