When is Ketoconazole Used for Prostate Cancer?

Nizoral® (ketoconazole) is an antifungal medication that can be used to treat certain fungal infections. However, several specific side effects of ketoconazole have led to it being used to treat certain other conditions, such as prostate cancer. When taken in high enough dosages, ketoconazole has the capability to prevent the body’s ability to transform cholesterol into other steroid hormones, including testosterone or cortisol. This property of the medication has led to it being considered an anti-androgen. Because the medicine decreases the creation of cortisol, an important steroid hormone for everyday functioning, ketoconazole is often administered with a steroid, to prevent levels from becoming too low in the body and causing side effects.

When used to treat prostate cancer, ketoconazole is typically used in individuals with metastatic or advanced prostate cancer (prostate cancer that has spread to other parts of the body) when other treatment options have proven to be ineffective. When used for prostate cancer treatment, ketoconazole is orally administered and comes in tablet form. However, when the medication is used to treat fungal infections and other conditions, it can also be administered topically via lotions or shampoos. Individuals taking ketoconazole should also be monitored for changes in liver functioning as well as changes in the electrical activity of the heart.

How does ketoconazole work?

Ketoconazole’s active ingredient is an anti-androgen at high dosages. Prostate cancer tumors are often fueled to grow by androgens, including testosterone. Ketoconazole inhibits an enzyme pathway that acts to transform cholesterol into steroid hormones like testosterone. Preventing the body from converting cholesterol to testosterone can lower the level of testosterone in the body. With lower amounts of testosterone present, tumor cells may be starved off and prevented from growing or proliferating further.

In addition, ketoconazole may be used during early stages of other hormone therapies, such as treatment with Gonadotropin-Releasing Hormone agonists, in order to block the initial surge of testosterone that can come along with these medications. The surge of testosterone at the beginning of some of these treatment methods can contribute to short term rapid tumor growth before it is halted, potentially leading to life-threatening issues such as spinal cord compression. Also, because ketoconazole may halt the conversion of cholesterol to certain cortisol molecules (including important steroids required for the body to function), individuals taking the medication may also be prescribed steroids to prevent the level of these important molecules from decreasing too much and causing side effects.

What are the possible side effects of ketoconazole?

Multiple clinical trials evaluated the safety and efficacy of ketoconazole. Possible side effects of ketoconazole include nausea, headache, stomach pain, and diarrhea. These are not all the possible side effects of ketoconazole. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with ketoconazole.

What to know about ketoconazole and prostate cancer?

Less common but more serious side effects can accompany ketoconazole including changes in liver functioning. Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their ketoconazole regimen. Alert your provider immediately if you notice any of the following symptoms:

  • Dark urine
  • Light colored stools
  • Yellowing of the skin and eyes
  • Stomach pain or tenderness
  • Fever or rash
  • Fatigue
  • Loss of appetite or sudden weight loss

Additionally, ketoconazole has the potential to cause changes in the heart’s electrical activity, called QT prolongation, causing the heart to beat irregularly. This commonly occurs when ketoconazole is taken with other specific medications. It is important to tell your provider about all medications you are currently taking, as well as to watch for symptoms including:

  • Feeling lightheaded, dizzy, or faint
  • Feeling your heart beating fast or irregularly

Before starting ketoconazole talk to your provider if you:

  • Have liver problems
  • Have problems with your heart or its electrical activity, including congenital long QT syndrome
  • Have muscle problems
  • Have any allergies, including medication allergies
  • Have adrenal insufficiency
  • Have any other medical conditions
  • Are currently taking any other medications (prescription and over-the-counter), vitamins, or herbal supplements

You should also contact your provider if you notice any signs of an allergic reaction to the medication, including chest pain or difficulty breathing. It is also important to consult the prescribing information for any other medications taken with ketoconazole, including steroids.

Ketoconazole usage information

Ketoconazole is administered orally and is often taken with steroids. Your provider will determine the appropriate dosage and administration schedule for you, as well as the appropriate dosage and administration of any other medications taken with ketoconazole. It is important to follow this schedule exactly as instructed, and not to stop taking ketoconazole or any accompanying medications on your own. Your provider will help you determine what course of action is best in the event that you miss a dose. If you take too much ketoconazole, contact your healthcare provider immediately.1

By providing your email address, you are agreeing to our privacy policy. We never sell or share your email address.

Written by: Casey Hribar | Last reviewed: March 2022