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Ketoconazole (Nizoral) — imidazole antifungal (topical shampoo)
An imidazole antifungal best known as a topical shampoo (Nizoral, 1% OTC / 2% Rx). Topically it is well-evidenced for seborrheic dermatitis and dandruff by suppressing scalp Malassezia, and is used off-label in androgenetic alopecia, where it shows modest anti-inflammatory and anti-DHT scalp effects. ORAL ketoconazole is a different story: the FDA and EMA severely restricted it in 2013 after reports of fatal liver injury and adrenal suppression, so systemic use is now rare. Prescription drug, not a supplement — informational only.
Prescription medication — not a dietary supplement
Ketoconazole (Nizoral) is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Ketoconazole (Nizoral) doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality meta-analyses and randomised trials published 1983–2026 with a typical study size of 9,052 participants.
Based on 189 studies · 4 meta-analyses · 170 RCTs · 9,152 total participants
Confidence
High confidenceBy outcome
Topical ketoconazole has solid evidence for seborrheic dermatitis and dandruff (anti-Malassezia), supported by a Cochrane review, plus a modest signal in androgenetic alopecia from small comparative and long-term-use studies. The score is held in the moderate range because the hair-loss evidence is limited and adjunctive, and because the ORAL form carries well-documented, sometimes fatal hepatotoxicity and adrenal suppression that led regulators to severely restrict it.
175 randomised trials
every one checked individually
Every randomised or controlled trial of Ketoconazole (Nizoral) indexed in PubMed, not a hand-picked subset. Meta-analyses and systematic reviews are deliberately excluded from this count: most of them cover many compounds at once, so counting them would inflate it.
PubMed · as of Jul 2026
16 trials ongoing or recruiting · 162 completed on ClinicalTrials.gov
40 of the completed trials have posted results
Registered trials show research momentum for Ketoconazole (Nizoral), not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Nov 2026
Ketoconazole is an imidazole antifungal that blocks fungal cytochrome-P450 lanosterol 14α-demethylase, depleting ergosterol and disrupting the fungal cell membrane.
On this site the relevant use is TOPICAL: as a shampoo (brand Nizoral, available 1% over-the-counter and 2% by prescription) it suppresses scalp Malassezia yeasts and has strong evidence for treating seborrheic dermatitis and dandruff — a Cochrane review of topical antifungals found ketoconazole more effective than placebo.
It is also used off-label in androgenetic (pattern) hair loss, where comparative and long-term-use studies suggest modest benefit: it reduces scalp inflammation and the drug also has intrinsic anti-androgen activity (it interferes with steroidogenesis and may lower local DHT signalling at the follicle), so it is sometimes added alongside minoxidil or finasteride in hair-loss regimens.
The honest framing of the hair-loss evidence is that it is modest, mostly from small or open-label studies, and that ketoconazole is an adjunct rather than a primary therapy. ORAL ketoconazole is an entirely different risk profile.
After its 1981 FDA approval, post-marketing reports of serious, sometimes fatal drug-induced liver injury, adrenal (glucocorticoid) suppression, and dangerous drug interactions accumulated; in 2013 the FDA and EMA severely restricted systemic ketoconazole, and it is now rarely used for fungal infections when safer alternatives exist.
Its steroidogenesis inhibition has historically been exploited off-label (Cushing's syndrome, prostate cancer), but always under specialist supervision with liver and hormone monitoring.
Ketoconazole is a prescription drug presented here for informational purposes only, not as a recommendation; the score reflects genuine topical efficacy in seborrheic dermatitis plus modest hair-loss signal, set against the well-documented systemic hepatotoxicity and adrenal risk that define its oral form.
Inhibits fungal lanosterol 14α-demethylase, depleting ergosterol and disrupting the membrane — suppressing scalp Malassezia yeasts implicated in dandruff and seborrheic dermatitis.
Has intrinsic anti-inflammatory activity at the scalp, dampening the microbial-driven inflammatory reaction around hair follicles thought to contribute to pattern hair loss.
Blocks cytochrome-P450 enzymes in steroid synthesis, which can lower androgen (DHT) signalling — the basis for its topical hair-loss adjunct use and its historical, restricted systemic use in Cushing's and prostate cancer (with adrenal-suppression risk).
How Ketoconazole (Nizoral) works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Avoid oral ketoconazole entirely; topical shampoo is far lower risk but discuss with a clinician.
Avoid the oral form; limit topical use to clinician-approved situations.
Oral ketoconazole requires clinician review for major medicine interactions. Review topical ketoconazole by its exact formulation and label; do not automatically transfer oral interaction rules or assume no systemic interaction from topical use.
Oral ketoconazole is a potent CYP3A4 inhibitor; markedly raises statin levels and rhabdomyolysis risk. Topical scalp use is not a meaningful source of this interaction.
Oral ketoconazole can raise levels of QT-prolonging drugs, risking dangerous arrhythmias.
Oral ketoconazole can increase anticoagulant effect via CYP inhibition; monitor INR.
Additive liver-injury risk with the oral form; avoid combining and monitor liver function.
Tip: Usually transient; reduce frequency or shorten contact time if irritation occurs.
Tip: Stop use if an allergic reaction develops. Dermatologist-supervised patch testing may help identify delayed contact allergy when clinically appropriate; it does not assess every immediate or systemic reaction.
Tip: A systemic-use risk of the oral form; requires specialist monitoring of cortisol/ACTH. For a topical product, exposure depends on its exact formulation, so use it according to its label.
Tip: Can be serious or fatal; the reason oral use is restricted. Requires liver-function monitoring and immediate discontinuation if enzymes rise or symptoms appear.
Ketoconazole (Nizoral) has an evidence score of 4/10 — emerging evidence based on 189 indexed studies, including 3 meta-analyses. An imidazole antifungal best known as a topical shampoo (Nizoral, 1% OTC / 2% Rx). Topically it is well-evidenced for seborrheic dermatitis and dandruff by suppressing scalp Malassezia, and is used off-label in androgenetic alopecia, where it shows modest anti-inflammatory and anti-DHT scalp effects. ORAL ketoconazole is a different story: the FDA and EMA severely restricted it in 2013 after reports of fatal liver injury and adrenal suppression, so systemic use is now rare. Prescription drug, not a supplement — informational only. Representative study: PMID 25933684.
Dosing for Ketoconazole (Nizoral): Topical shampoo: apply 1% (OTC) or 2% (prescription) to the scalp, lather, leave on ~3–5 minutes, rinse, twice weekly for seborrheic dermatitis/dandruff (less often for maintenance). Off-label hair-loss use follows the same 2–3×/week shampoo schedule, typically alongside minoxidil/finasteride. ORAL ketoconazole is a restricted systemic drug and is NOT a self-directed regimen — used only by specialists with liver and adrenal monitoring. A prescription drug; informational only, not a supplement. Individual needs vary, so check the right dose for you with a healthcare provider.
Timing is flexible for Ketoconazole (Nizoral) — consistent daily use matters more than the time of day. Topical shampoo used in the shower 2–3 times a week; leave on the scalp a few minutes before rinsing to allow contact time.
Ketoconazole (Nizoral) should be used with caution — talk to a healthcare provider before taking it. Reported side effects include adrenal (glucocorticoid) suppression (oral), drug-induced liver injury (oral), scalp itching, irritation, or dryness (topical). How often they occur is not established for all of them. Use caution if any of these apply to you: ORAL ketoconazole: pre-existing or active liver disease (high risk of further hepatotoxicity); Known hypersensitivity to ketoconazole or imidazole antifungals; Oral use is contraindicated with many CYP3A4-dependent drugs (QT-prolonging agents, certain statins, etc.).
What side effects does Ketoconazole (Nizoral) have?Don't take this if…
Finasteride (topical)
Too few graded studiesThe same drug as oral finasteride, applied to the scalp — with a systemic-sparing claim that the pharmacokinetic data only partly supports.
Finasteride
Too few graded studiesA prescription 5α-reductase type-II inhibitor that lowers DHT to treat male pattern hair loss (1 mg, Propecia) and benign prostatic hyperplasia (5 mg, Proscar). The hair and prostate benefits are well-proven in large RCTs. The honest caveats are real and prominent: sexual side effects (erectile dysfunction, decreased libido) in a minority of men, a disputed but important 'post-finasteride syndrome' with persistent symptoms, and a depression/suicidality safety signal in pharmacovigilance data. It is NOT a longevity drug.
Minoxidil (oral & topical)
Too few graded studiesA potassium-channel-opening vasodilator — originally an oral antihypertensive — whose well-documented hypertrichosis side effect made it the first FDA-approved hair-loss drug. Topical 2–5% (Rogaine) is OTC and proven in androgenetic alopecia; low-dose ORAL minoxidil (LDOM, ~0.25–5 mg) is an off-label, rapidly adopted alternative with real but generally mild cardiovascular/hypertrichosis side effects. A drug, not a supplement — and not a longevity compound.
Dutasteride
Too few graded studiesA dual 5α-reductase (type I + II) inhibitor approved for benign prostatic hyperplasia and used off-label for male pattern hair loss. It suppresses DHT more deeply than finasteride (which blocks only type II), and at 2.5 mg (five times the approved dose) it beat finasteride for hair count in one 24-week trial. It carries the same sexual and mood side-effect concerns as finasteride — with a much longer half-life, so any persistent effects clear more slowly. A prescription drug, not a supplement, and not a longevity drug.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 189 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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