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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
Most Ketoconazole (Nizoral) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from high-quality meta-analyses and randomised trials published 1983–2025.
Based on 181 studies · 3 meta-analyses · 170 RCTs
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.
182 rigorous studies
175 randomized trials · 3 meta-analyses · 4 systematic reviews
Our evidence rating for Ketoconazole (Nizoral) is accountable to this entire body of rigorous research indexed in PubMed — not a hand-picked subset.
PubMed · as of Jul 2026
14 trials ongoing or recruiting · 161 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for Ketoconazole (Nizoral), not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed.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 Aug 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 has major CYP3A4 interactions — a clinician must review the full drug list. Topical use is minimal-absorption and low-interaction.
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: Discontinue if an allergic reaction develops; patch testing can confirm sensitivity.
Tip: A systemic-use risk; requires specialist monitoring of cortisol/ACTH. Not relevant to the shampoo.
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 171 indexed studies, including 1 meta-analysis. 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 23895707.
The commonly studied dose of Ketoconazole (Nizoral) is 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 — start at the lower end of the range and adjust based on how you respond.
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. The most commonly reported side effects are scalp itching, irritation, or dryness (topical), contact dermatitis / hair-texture change (topical), adrenal (glucocorticoid) suppression (oral). 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.).
Finasteride
Mostly mechanism / observationalA 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)
Mostly mechanism / observationalA 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
Mostly mechanism / observationalA 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 head-to-head it beats finasteride for hair regrowth. 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.
Tretinoin (Retin-A)
Mostly mechanism / observationalA prescription TOPICAL retinoid (Retin-A, Renova) — the acid form of vitamin A and the gold-standard, best-evidenced topical treatment for photoaging and acne. Multiple double-blind RCTs show it reduces fine wrinkles, mottled hyperpigmentation, and roughness over months, with histologic increases in dermal collagen. Caveats: retinoid dermatitis (irritation, peeling, dryness), photosensitivity, and it is CONTRAINDICATED IN PREGNANCY. Prescription drug, not a supplement; distinct from weaker OTC 'retinol' cosmetics.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 181 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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