Nausea and vomiting may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these rare but serious side effects occur: headache, vision changes, mental/mood changes (such as depression, thoughts of suicide).

Although unlikely, when ketoconazole is used at high doses, it may cause an adrenal gland problem (adrenal insufficiency), a decrease in testosterone levels, and a decrease in sperm production. These effects usually go away after ketoconazole treatment is stopped. Tell your doctor immediately if any of these unlikely but serious side effects occur: unusual tiredness, weakness, dizziness upon standing, persistent nausea/vomiting, diarrhea, stomach pain, loss of appetite, weight loss, decreased sexual interest or ability, enlarged/tender breasts in men.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the Nizoral (ketoconazole) Side Effects Center for a complete guide to possible side effects »

PRECAUTIONS: Before taking ketoconazole, tell your doctor or pharmacist if you are allergic to it; or to other azole antifungal drugs (such as fluconazole, itraconazole); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver problems, alcohol use, low testosterone levels, decreased adrenal gland function problems (such as low cortisol levels, Addison's disease, adrenal insufficiency), little or no stomach acid production (achlorhydria).

Do not drink alcohol while taking this medication because alcohol increases the risk of serious liver problems. Avoiding alcohol will also decrease the risk of a rare reaction with ketoconazole that may result in flushing, headache, and nausea.

During pregnancy, this medication should be used only when clearly needed. It may cause harm to an unborn baby if taken during the first 3 months of pregnancy. Discuss the risks and benefits with your doctor.

This medication passes into breast milk. However, this drug is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.