Ketoconazole; Uses, Dosage, Side Effects, Interactions, Pregnancy

Last updated: February 7, 2026Reviewed date: February 7, 2026Reading time: 8 min read
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Ketoconazole is a synthetic derivative of phenylpiperazine with broad antifungal properties and potential antineoplastic activity. Ketoconazole inhibits sterol 14-a-dimethylase, a microsomal cytochrome P450-dependent enzyme, thereby disrupting the synthesis of ergosterol, an important component of the fungal cell wall. (NCI04) Ketoconazole is an imidazole fungicidal agent with a very broad spectrum of activity against many...

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

এই তথ্য শিক্ষা ও সচেতনতার জন্য। এটি ডাক্তারি পরীক্ষা, রোগ নির্ণয় বা প্রেসক্রিপশনের বিকল্প নয়।

Article Summary

Ketoconazole is a synthetic derivative of phenylpiperazine with broad antifungal properties and potential antineoplastic activity. Ketoconazole inhibits sterol 14-a-dimethylase, a microsomal cytochrome P450-dependent enzyme, thereby disrupting the synthesis of ergosterol, an important component of the fungal cell wall. (NCI04) Ketoconazole is an imidazole fungicidal agent with a very broad spectrum of activity against many fungal species that is used for the treatment of superficial and systemic fungal infections. Ketoconazole is a well-documented cause of clinically apparent...

Key Takeaways

  • This article explains Mechanism of Action of Ketoconazole in simple medical language.
  • This article explains  Indications of Ketoconazole in simple medical language.
  • This article explains Therapeutic Indications in simple medical language.
  • This article explains Contraindications of Ketoconazole in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
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Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

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Definition

Ketoconazole is a synthetic derivative of phenylpiperazine with broad antifungal properties and potential antineoplastic activity. Ketoconazole inhibits sterol 14-a-dimethylase, a microsomal cytochrome P450-dependent enzyme, thereby disrupting the synthesis of ergosterol, an important component of the fungal cell wall. (NCI04)

Ketoconazole is an imidazole fungicidal agent with a very broad spectrum of activity against many fungal species that is used for the treatment of superficial and systemic fungal infections. Ketoconazole is a well-documented cause of clinically apparent acute drug-induced liver injury and is no longer recommended as a first line antifungal agent.
Broad spectrum antifungal agent used for long periods at high doses, especially in immunosuppressed patients. Ketoconazole is sold commercially as a tablet for oral administration (although this use has been discontinued in a number of countries), and in a variety of formulations for topical administration, such as creams (used to treat tinea; cutaneous candidiasis, including candidal paronychia; and pityriasis versicolor) and shampoos (used primarily to treat dandruff—seborrhoeic dermatitis of the scalp) .

Mechanism of Action of Ketoconazole

Ketoconazole interacts with 14-α demethylase, a cytochrome P-450 enzyme necessary for the conversion of lanosterol to ergosterol. This results in inhibition of ergosterol synthesis and increased fungal cellular permeability. Other mechanisms may involve the inhibition of endogenous respiration, interaction with membrane phospholipids, inhibition of yeast transformation to mycelial forms, inhibition of purine uptake, and impairment of triglyceride and/or phospholipid biosynthesis. Ketoconazole can also inhibit the synthesis of thromboxane and sterols such as aldosterone, cortisol, and testosterone.

 Indications of Ketoconazole

  • Blastomycosis
  • Candidiasis, Cutaneous
  • Candiduria
  • Chromomycosis
  • Coccidioidomycosis
  • Dandruff
  • Histoplasmosis
  • Oral candida
  • Paracoccidioidomycosis
  • Pityriasis Versicolor
  • Seborrheic dermatitis
  • Tinea corporis
  • Tinea cruris
  • Tinea pedis
  • Recalcitrant cutaneous dermatophyte infection
  • Severe cutaneous dermatophyte infection
  • Chronic mucocutaneous candidiasis
  • Dermatophytosis
  • Esophageal candidiasis
  • Onychomycosis, Fingernail
  • Onychomycosis, toenail
  • Oral thrush
  • Paracoccidioidomycosis
  • Tinea corporis
  • Tinea versicolor
  • Vaginal yeast infection

Therapeutic Indications

  • For the treatment of the following systemic fungal infections: candidiasis, chronic mucocutaneous candidiasis, oral thrush, candiduria, blastomycosis, coccidioidomycosis, histoplasmosis, chromomycosis, and paracoccidioidomycosis.
  • Treatment of Cushing’s syndrome
  • Treatment of granulosa cell tumors
  • Ketoconazole HRA is indicated for the treatment of endogenous Cushing’s syndrome in adults and adolescents above the age of 12 years.

Contraindications of Ketoconazole

  • Have known hypersensitivity to other azole medicines such as ketoconazole;
  • Are taking terfenadine, if 400 mg per day multidose of fluconazole is administered;
  • Concomitant administration of ketoconazole and quinidine, especially when ketoconazole is administered in high dosages;
  • Take SSRIs such as fluoxetine or sertraline.

Dosage of Ketoconazole

Strengths:

Tablets: 200 mg; Shampoo: 1% and 2%; Cream: 2%, Gel: 2%, Foam: 2%

Blastomycosis

  • Initial dose: 200 mg orally once a day
  • If clinical responsiveness insufficient within expected time: Dose may be increased to 400 mg orally once a day.
  • Duration of therapy: 6 months (usual duration for systemic infection)

Chromomycosis

  • Initial dose: 200 mg orally once a day
  • If clinical responsiveness insufficient within expected time: Dose may be increased to 400 mg orally once a day.

Coccidioidomycosis

  • Initial dose: 200 mg orally once a day
  • If clinical responsiveness insufficient within expected time: Dose may be increased to 400 mg orally once a day.
  • Duration of therapy: 6 months (usual duration for systemic infection)

Histoplasmosis

  • Initial dose: 200 mg orally once a day
  • If clinical responsiveness insufficient within expected time: Dose may be increased to 400 mg orally once a day.
  • Duration of therapy: 6 months (usual duration for systemic infection)

Blastomycosis

  • 2 years or older: 3.3 to 6.6 mg/kg orally once a day
  • Duration of therapy: 6 months (usual duration for systemic infection)

Chromomycosis

  • 2 years or older: 3.3 to 6.6 mg/kg orally once a day
  • Duration of therapy: 6 months (usual duration for systemic infection)

Coccidioidomycosis

  • 2 years or older: 3.3 to 6.6 mg/kg orally once a day
  • Duration of therapy: 6 months (usual duration for systemic infection)

Paracoccidioidomycosis

  • 2 years or older: 3.3 to 6.6 mg/kg orally once a day
  • Duration of therapy: 6 months (usual duration for systemic infection)

Side Effects of Ketoconazole

The most common 

Common

Rare

Interactions of Ketoconazole

Kitoconazole may interact with following drugs ,supplyments & may change the efficacy of drugs

Interactions that can make your drugs less effective

When ketoconazole is less effective: When ketoconazole is used with certain drugs, it may not work as well to treat your condition. This is because the amount of ketoconazole in your body may be decreased. Examples of these drugs include:

  • Ranitidine, famotidine, cimetidine, pantoprazole, omeprazole, and rabeprazole. You should take ketoconazole with an acidic beverage, such as a non-diet soda, if you take these drugs together.
  • Aluminum hydroxide. You should take this drug 1 hour before or 2 hours after taking ketoconazole.
  • Antibiotics, such as isoniazid and rifabutin
  • Anticonvulsants, such as carbamazepine and phenytoin
  • Antivirals, such as efavirenz and nevirapine
  • Carbamazepine. Your doctor may monitor your carbamazepine levels.

Pregnancy & Lactation

FDA Pregnancy category C 

Ketoconazole falls into category C. In animal studies, pregnant animals were given this medication and had some babies born with problems. There are no well-controlled studies that have been done in humans with ketoconazole, though. Therefore, this medication may be used if the potential benefits to the mother outweigh the potential risks to the unborn child.

Lactation

It is not known if ketoconazole crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using ketoconazole.

References

Ketoconazole; Uses, Dosage, Side Effects, Interactions, Pregnancy

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Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Orthopedic / spine specialist, physical medicine doctor, or qualified clinician
Tests to discuss with doctor
  • Neurological examination for leg power, sensation, reflexes, and straight leg raise
  • X-ray only if injury, deformity, long-lasting pain, or doctor suspects bone problem
  • MRI discussion if severe nerve symptoms, weakness, bladder/bowel problem, or persistent symptoms
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Is physiotherapy, posture correction, or activity modification needed?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Ketoconazole; Uses, Dosage, Side Effects, Interactions, Pregnancy

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

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Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

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