Ketoconazole - Oral: Uses, Side Effects, Dosages - Verywell Health
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What Is Ketoconazole?
Ketoconazole is an orally prescribed medication used to treat certain fungal infections, mainly systemic (bloodstream) infections, and is approved for adults 18 and older. Ketoconazole is categorized within a class of antifungals called imidazoles and is used when other medications are unavailable or cannot be tolerated.
This antifungal works by blocking a specific fungal protein called cytochrome P-450-mediated 14 alpha-lanosterol demethylase enzyme.
This protein is responsible for turning lanosterol—a type of steroid—into ergosterol. Without ergosterol, the weakened fungal cell wall starts to fall apart.
Ketoconazole tablets are only available as the ketoconazole generic version. Aside from tablets, ketoconazole as a primary ingredient is also available under varying brand names, specifically in the form of topical products, including shampoos, gels, creams, and foams.
Drug Facts
Generic Name: Ketoconazole
Brand Name(s): N/A
Drug Availability: Prescription
Therapeutic Classification: Imidazole antifungal
Available Generically: Yes
Controlled Substance: N/A
Administration Route: Oral
Active Ingredient: Ketoconazole
Dosage Form(s): Tablet
What Is Ketoconazole Used For?
The Food and Drug Administration (FDA) approved Ketoconazole as a treatment option for when other effective antifungals aren't available or cannot be tolerated regarding systemic fungal infections.
Examples of these infections may include:
- Blastomycosis: The Blastomyces fungus is responsible for blastomycosis infections. You can usually find this fungus in moist soil with dead leaves in the midwestern, southeastern, and south-central United States (U.S.). You may get this infection by breathing in fungal spores in this type of environment.
- Chromomycosis: This infection might be caused by a number of pigmented (colored) fungi, such as Fonsecaea, Cladophialophora, and Phialophora. These fungi can be found in soil and dead leaves of tropical or subtropical environments. They can enter your body through a skin injury.
- Coccidioidomycosis (Valley fever): The Coccidioides fungus is responsible for Valley fever infections. You can find this fungus in the soil of the southwestern U.S. You may also find this fungus in certain parts of Mexico, Central America, and South America. The fungus may enter your body if you breathe in a lot of dust in these areas.
- Histoplasmosis: The Histoplasma fungus causes histoplasmosis. You can find it in the central and eastern U.S. with soil that has a lot of bird or bat droppings. You can also find it in certain parts of Africa, Asia, Australia, Central America, and South America. Histoplasma may enter your body if you breathe in the fungal spores in the air.
- Paracoccidioidomycosis: Paracoccidioides is the fungus that causes paracoccidioidomycosis. You might get this infection if you live, visit, or work outdoors in the rural parts of Central and South America. You can get this infection by breathing in the fungus in these areas.
How to Take Ketoconazole
Take Ketoconazole by mouth once daily.
Ketoconazole requires an acidic environment in your stomach to get absorbed into your bloodstream. Therefore, if you take medications that make your stomach more basic (less acidic), your body will have lower ketoconazole levels to do its job.
For this reason, you may also need to take ketoconazole with an acidic beverage (e.g., non-diet soda) if you also take these medications, such as Pepcid (famotidine) or Nexium (esomeprazole).
Storage
When you receive ketoconazole tablets from the pharmacy, keep them at room temperature between 68 degrees to 77 degrees F—with a short-term safety storage range between 59 degrees to 86 degrees F.
Keep your medications tightly closed and out of the reach of children and pets, ideally locked in a cabinet or closet. Try to keep ketoconazole tablets dry. Don't store your medication in the bathroom.
Try to avoid pouring unused and expired drugs down the drain or in the toilet. Visit the FDA's website to know where and how to discard all unused and expired drugs. You can also find disposal boxes in your area.
Ask your healthcare provider if you have any questions about the best ways to dispose of your medications.
If you plan to travel with ketoconazole, get familiar with your final destination's regulations. Checking with the U.S. embassy or consulate might be a helpful resource. In general, however, make a copy of your ketoconazole prescription.
It's also a good idea to keep your medication in its original container from your pharmacy with your name on the label.
If you have any questions about traveling with your medicine, be sure to ask your pharmacist or healthcare provider.
Off-Label Uses
You may see healthcare providers recommend ketoconazole for the following off-label uses:
- Cushing syndrome: Ketoconazole may help treat and manage Cushing syndrome, which is a medical condition of too much cortisol hormone. This may happen from long-term corticosteroid (steroid) use.
- Advanced prostate cancer: Some people with advanced prostate cancer might benefit from antiandrogen withdrawal (AAW). You may see ketoconazole in combination with hydrocortisone to treat this group of individuals.
How Long Does ketoconazole Take to Work?
It might take roughly six months of ketoconazole therapy to clear a systemic fungal infection.
What Are the Side Effects of Ketoconazole?
This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 800-FDA-1088.
Common Side Effects
Common side effects with ketoconazole tablets may include:
Severe Side Effects
The FDA assigned a black box warning to ketoconazole tablets.
This medication shouldn't be used to treat onychomycosis (fungal nail infections) and cutaneous dermatophyte infections (fungal infections involving hair, skin, and nails). Ketoconazole tablets also shouldn't be used for Candida yeast (type of fungus) infections, which may cause thrush or vaginal candidiasis.
This medication has the potential for serious side effects, such as abnormal heart rhythm and liver toxicity. For this reason, ketoconazole tablets are only typically used when other effective antifungals aren't available or tolerated.
Notify your healthcare provider if common side effects become severe or don't go away. Get medical help right away if you develop the following serious side effects:
- Severe allergic reaction: If you have a severe allergic reaction to ketoconazole, symptoms may include rash, swelling, and breathing difficulties.
- Abnormal heart rhythm: Ketoconazole raises your risk of having an abnormal heart rhythm. This risk is further increased when ketoconazole is combined with other medications with a similar side effect. Symptoms of an abnormal heart rhythm may include feeling faint, dizzy, or lightheaded. You may also notice your heartbeat is fast or irregular.
- Adrenal insufficiency: Adrenal insufficiency is sometimes known as Addison's disease. People with this medical condition don't make enough of certain hormones, such as cortisol. As a result, symptoms of adrenal insufficiency may include dizziness, tiredness, weakness, nausea, and vomiting.
- Liver toxicity: Ketoconazole is linked to liver toxicity. If you're experiencing worsening liver function, symptoms may include dark-colored urine and yellowing of the eyes or skin.
- Low sperm count: At high doses, ketoconazole is linked to low testosterone levels and low sperm count. These effects, however, are reversible.
Call 911 if your symptoms feel life-threatening.
Long-Term Side Effects
Liver toxicity is a potential long-term side effect of ketoconazole. While rare, this side effect can become severe and require a liver transplant.
Report Side Effects
Ketoconazole tablets may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.
If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).
Dosage: How Much Ketoconazole Should I Take?
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For fungal infections:
- Adults—At first, 200 milligrams (mg) once a day. Your doctor may increase your dose as needed.
- Children 2 years of age and older—Dose is based on body weight and must be determined by your doctor. The dose is usually 3.3 to 6.6 milligrams (mg) per kilogram (kg) of body weight per day.
- Children younger than 2 years of age—Use and dose must be determined by your doctor.
- For fungal infections:
Modifications
The following modifications (changes) should be kept in mind when using ketoconazole:
Severe allergic reaction: Avoid using ketoconazole if you have a known allergy to it or any of its ingredients. Ask your healthcare provider for a complete list of the ingredients if you're unsure.
Pregnancy: In rat animal studies, ketoconazole was found to have negative effects on the fetus. We don't know enough about the safety and effectiveness of ketoconazole in pregnant people and their unborn fetuses.
Discuss with your healthcare provider if you plan to become pregnant or are pregnant. Ketoconazole should only be taken during pregnancy if the potential benefits outweigh the risks.
Breastfeeding: Ketoconazole may be present in human breast milk. Due to ketoconazole's potential effects on the liver, there is little information about the effects and safety of ketoconazole in human breast milk and nursing babies.
However, this isn't a reason to stop ketoconazole if the breastfeeding parent needs the medication.
If you're going to take ketoconazole tablets while breastfeeding, there are ways to limit this medication from reaching your breastmilk. Consider taking ketoconazole right before your baby's longest sleeping period. You can also avoid nursing your child for two to five hours after taking ketoconazole.
Talk with your healthcare provider if you plan to breastfeed. They will help you weigh the benefits and risks of ketoconazole while nursing. They can also discuss different ways to feed your baby.
Older adults over 65: There is limited information available to assess response differences to ketoconazole between older and younger adults. However, older adults with several medical conditions or taking several medications should use caution. In addition, older adults might be more sensitive to side effects from medications.
Children: There's little information available about the effectiveness and safety of ketoconazole tablets in children, especially those under 2 years of age. This medication should only be used in children if the benefits outweigh the risks. When used in children, ketoconazole dosage is based on weight.
Kidney problems: Kidney function doesn't affect ketoconazole dosages.
Liver problems: If you have acute or chronic (long-term) liver disease, ketoconazole tablets aren't recommended for you.
Missed Dose
If you accidentally forgot your ketoconazole dose, take it as soon as you remember. If it's already close to your next scheduled dose, then skip the missed dose and take the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.
Try to find ways that work for you to help yourself remember to routinely keep your appointments and take your medication. If you miss too many doses, ketoconazole might be less effective.
Overdose: What Happens If I Take Too Much Ketoconazole?
There is limited information available about ketoconazole overdoses. A suspected overdose, however, may likely result in the following serious side effects:
- Adrenal insufficiency, a medical condition of low amounts of certain hormones—like cortisol
- Liver toxicity
- Erectile dysfunction (ED)
If you think that you're experiencing an overdose or life-threatening symptoms, seek immediate medical attention.
What Happens If I Overdose on Ketoconazole?
If you think you or someone else may have overdosed on ketoconazole tablets, call a healthcare provider or the Poison Control Center (800-222-1222).
If someone collapses or isn't breathing after taking ketoconazole, call 911 immediately.
Precautions
It is very important that your doctor check your or your child's progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.
If your or your child's symptoms do not improve, or if they become worse, check with your doctor. You may need to take this medicine for several months before your infection gets better.
Do not use this medicine together with alprazolam, cisapride, colchicine, disopyramide, dofetilide, dronedarone, eplerenone, felodipine, irinotecan, lovastatin, lurasidone, methadone, nisoldipine, oral midazolam, pimozide, quinidine, ranolazine, simvastatin, terfenadine, tolvaptan, triazolam, or ergot medicines (such as dihydroergotamine, ergometrine, ergotamine, methylergometrine). Using these medicines together may cause serious unwanted effects.
Liver problems may occur while you are taking this medicine. Check with your doctor right away if you are having more than one of these symptoms: abdominal or stomach pain or tenderness, clay-colored stools, dark urine, decreased appetite, fever, headache, itching, loss of appetite, nausea and vomiting, skin rash, swelling of the feet or lower legs, unusual tiredness or weakness, or yellow eyes or skin.
Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem such as QT prolongation.
This medicine may cause serious allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.
Avoid drinking alcohol while you are using this medicine.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
What Are Reasons I Shouldn't Take Ketoconazole?
Before using ketoconazole, talk with your healthcare provider if any of the following applies to you:
Severe allergic reaction: If you have a severe allergic reaction to ketoconazole or any of its ingredients, this medication isn't a viable option for you.
Pregnancy: We don't know enough about the safety and effectiveness of ketoconazole in pregnant people and on their unborn fetuses. Discuss with your healthcare provider about the benefits and risks of ketoconazole during pregnancy.
Breastfeeding: Ketoconazole is present in human breastmilk, but there is little additional information about its effects and safety in nursing babies. This isn't a reason to stop ketoconazole, however, if the breastfeeding parent needs the medication.
If you're going to take ketoconazole tablets while breastfeeding, there are ways to limit this medication from reaching your breastmilk.
Consider taking ketoconazole right before your baby's longest sleeping period. You can also avoid nursing your child for two to five hours after taking ketoconazole. Talk with your healthcare provider to weigh the benefits and harms of ketoconazole while breastfeeding.
Older adults over 65: There is limited information available to assess response differences to ketoconazole between older and younger adults. In general, older adults should use caution.
Children: There's little information available about the effectiveness and safety of ketoconazole tablets in children, especially those under 2 years of age. This medication should only be used in children if the benefits outweigh the risks. When used in children, ketoconazole dosage is based on weight.
Kidney problems: Kidney function doesn't affect ketoconazole dosages.
Liver problems: If you have acute or chronic (long-term) liver disease, ketoconazole tablets aren't recommended for you.
Certain medications: Ketoconazole tablets shouldn't be taken with numerous medications.
What Other Medications May Interact With Ketoconazole?
In general, ketoconazole has a lot of drug interactions. The following are some key ones:
Medications that cause abnormal heart rhythm: Ketoconazole may raise your risk of abnormal heart rhythm. This risk is further increased with medicines that may have the same side effect. For this reason, avoid combining ketoconazole with these medications, which may include Tikosyn (dofetilide), Multaq (dronedarone), and Ranexa (ranolazine) heart medications.
Certain benzodiazepines: Ketoconazole can raise benzodiazepine levels, resulting in a higher risk of excessive drowsiness and sleepiness. Avoid taking ketoconazole with certain benzodiazepines, such as a short-term sleep medication called Halcion (triazolam).
Certain statins: Statins are typically used for high cholesterol. Combining ketoconazole with certain statins—like Zocor (simvastatin)—raises your risk of severe muscle-related side effects. For this reason, this combination should be avoided.
Ergotamine medications: Ergotamines are medication options used for migraine relief. Ketoconazole may raise ergotamine levels and increase your chances of severe side effects, such as dangerously low blood flow to your brain. Avoid combining these medications.
Medications that make the stomach less acidic: Medications that make the stomach environment more basic (less acidic) will lower ketoconazole levels, making it less effective. Examples of these medications include Pepcid AC (famotidine) and Nexium (esomeprazole). If you're going to take ketoconazole with these medications, you may need to take ketoconazole with an acidic drink, such as a non-diet soda.
For more detailed information about medication interactions with ketoconazole, talk with your pharmacist or healthcare provider.
And be sure to talk with your healthcare provider about any other medicines you take or plan to take, including over-the-counter (OTC), nonprescription products, vitamins, herbs, or plant-based medicines.
What Medications Are Similar?
Ketoconazole is an azole antifungal, specifically an imidazole type of azole antifungal. The following are other imidazole antifungals that also have oral (by mouth) and topical dosage forms.
- Clotrimazole
- Miconazole
As previously mentioned, clotrimazole and miconazole are available as oral products. Unlike ketoconazole, however, they're not used for systemic infections.
Instead, they're typically used to treat Candida yeast (type of fungus) infections, which cause thrush. Clotrimazole and miconazole are also available as vaginal products for vaginal Candida yeast infections.
While these imidazoles mainly treat thrush or vaginal Candida infections, ketoconazole tablets shouldn't be used to treat these types of Candida infections. Ketoconazole tablets also carry a black box warning.
All three imidazoles, however, are available in topical versions that can be used for certain fungal skin infections, such as jock itch, athlete's foot, and ringworm of the body. Topical ketoconazole can also be used for skin Candida infections and another fungal skin infection called tinea versicolor.
How Can I Stay Healthy While Taking Ketoconazole?
If you're taking ketoconazole tablets, chances are a systemic fungal infection has negatively affected your quality of life. Having this type of infection has its challenges.
You may have tried different approaches or treatments. Refer to some general tips to support your health. There are also some recommendations to prevent this infection, such as:
- Take antifungals as recommended by your healthcare provider.
- Try to limit activities that involve interrupting the soil in specific areas that have certain potential bloodstream fungi, such as Blastomyces.
- Try to limit activities that involve disrupting the soil or chopping wood in specific areas that have bird or bat droppings to prevent histoplasmosis.
- Prevent histoplasmosis by limiting the following activities, such as cleaning chicken coops and exploring caves. Other activities to avoid include working in old buildings—from cleaning to remodeling and tearing down these buildings.
- Get in touch with professional companies that specialize in removing large amounts of bird or bat droppings.
- Try to avoid specific dusty areas with Coccidioides that may cause bloodstream infections. If you can't avoid these areas, consider wearing an N95 mask.
- Keep your windows closed, use air filtration systems and stay inside if there are dust storms in specific areas with Coccidioides.
- Try to limit gardening and similar activities where you're likely going to be close to dirt or dust in specific areas that have Coccidioides.
- Use soap and water to clean skin injuries to decrease your chances of getting certain bloodstream fungal infections, such as coccidioidomycosis (Valley fever).
