Ketoconazole belongs to the family of medications called antifungals. It is used to treat certain types of serious fungal infections. Ketoconazole is used to treat both internal (in the body) and external (on the skin) fungal infections. Ketoconazole works by preventing the fungus from making normal cell walls, thereby stopping fungal growth.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult dose of ketoconazole is 200 mg once daily with a meal. Occasionally, adults may need to take 400 mg daily. Children's doses are based on their body weight.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

The length of treatment depends on the response to the medication as well as the condition being treated; it can range from 1 week to 12 months.

Ketoconazole should not be taken within 2 hours of taking an antacid. People who have a decreased amount of stomach acid due to medical conditions or certain medications (e.g., H2-antagonists or proton pump inhibitors) should take ketoconazole along with a cola beverage.

It is important to take this medication exactly as prescribed by the doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take ketoconazole if you:

• are allergic to ketoconazole or any ingredients of the medication
• are pregnant, or may become pregnant, unless effective forms of birth control are used
• are taking any of the following medications:
• atorvastatin
• lovastatin
• midazolam (taken by mouth)
• pravastatin
• simvastatin
• triazolam
• have reduced liver function

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• diarrhea
• headache
• nausea
• skin rash
• vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• signs of heart problems (e.g., fast, irregular heartbeat or pulse, chest pain, sudden weight gain, difficulty breathing, leg swelling)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools, skin rash, itching)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• symptoms of a severe skin rash (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Liver function: Ketoconazole may reduce liver function and can cause liver failure. Depending on how long you need to take the medication, your doctor may order blood tests to check your liver function. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: Ketoconazole may cause harm to an unborn baby. This medication should not be used by pregnant women unless the benefits outweigh the risks. Women who may become pregnant must use an effective form of birth control while taking ketoconazole. If you are a woman of childbearing age, discuss appropriate and effective forms of birth control with your doctor.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and taking ketoconazole, it may affect your baby. Breast-feeding people are encouraged to stop breast-feeding before starting therapy with ketoconazole. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children. The effect of ketoconazole on hormone production, vitamin D use by the body, and calcium and phosphorus levels in the blood may interfere with the normal growth and development of a child. Ketoconazole should not be given to children unless the benefits outweigh the risks.

There may be an interaction between ketoconazole and any of the following:

• alcohol
• aliskiren
• alitretinoin
• almotriptan
• alpha-blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• antiarrhythmics (e.g., amiodarone, disopyramide, dronedarone, procainamide, propafenone)
• antipsychotics (e.g., cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apalutamide
• apixaban
• aprepitant
• atovaquone
• avacopan
• other "azole" antifungals (e.g., itraconazole, voriconazole)
• benzodiazepines (e.g., alprazolam, clonazepam, diazepam, midazolam, triazolam)
• bilastine
• bosentan
• bromocriptine
• buprenorphine
• buspirone
• butorphanol
• calcium channel blockers (e.g., amlodipine, diltiazem, felodipine, nifedipine, verapamil)
• calcium carbonate
• calcitriol
• cancer medications (e.g., cyclophosphamide, docetaxel, doxorubicin, etoposide, imatinib, irinotecan, vinblastine, vincristine)
• cannabis
• carbamazepine
• CF transmembrane regulators (e.g., elexacaftor, ivacaftor, lumacaftor, tezacaftor)
• cimetidine
• clindamycin
• clobazam
• cobicistat
• colchicine
• inhaled corticosteroids (e.g., budesonide, ciclesonide, fluticasone)
• oral corticosteroids (e.g., dexamethasone, methylprednisolone, prednisone)
• cyclosporine
• cyproterone
• dabigatran
• darifenacin
• darolutamide
• digoxin
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide)
• domperidone
• dutasteride
• edoxaban
• elagolix
• eliglustat
• eletriptan
• enzalutamide
• eplerenone
• ergot alkaloids (e.g., ergotamine, dihydroergotamine)
• estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
• everolimus
• fesoterodine
• finerenone
• fingolimod
• flibanserin
• galantamine
• guanfacine
• H2 antagonists (e.g., cimetidine, famotidine, ranitidine)
• hepatitis C antivirals (e.g., elbasvir and grazoprevir, glecaprevir and pibrentasvir, ledipasvir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine, rilpivirine)
• HIV protease inhibitors (e.g., atazanavir, darunavir, lopinavir, ritonavir)
• isoniazid
• ivabradine
• lemborexant
• levomilnacipran
• lidocaine
• lomitapide
• loratadine
• macitentan
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• maraviroc
• methadone
• mifepristone
• mirtazapine
• modafinil
• nadolol
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone, tramadol)
• nirmatrelvir and ritonavir
• ospemifene
• oxybutynin
• phenobarbital
• phenytoin
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pimecrolimus
• praziquantel
• primidone
• progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
• protein kinase inhibitors (e.g., bosutinib, dasatinib, imatinib, nilotinib)
• proton pump inhibitors (e.g., omeprazole, esomeprazole, lansoprazole)
• quinine
• repaglinide
• rifabutin
• rifampin
• rifaximin
• riociguat
• rivaroxaban
• roflumilast
• rupatadine
• saccharomyces boulardii
• saxagliptin
• St. John's wort
• salmeterol
• sirolimus
• sodium bicarbonate
• solifenacin
• sotalol
• sucralfate
• "statin" medications (e.g., atorvastatin, lovastatin, simvastatin)
• tacrolimus
• tenofovir
• ticagrelor
• tofacitinib
• tolterodine
• tolvaptan
• trazodone
• tretinoin
• venetoclax
• vilanterol
• vitamin A
• warfarin
• zolpidem
• zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.