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Imidazole antifungal Pregnancy: UK SPC §4.6, verbatim: 'Ketoconazole 2% w/w shampoo is not detected in plasma after chronic shampooing or topical application. Ketoconazole 2% w/w shampoo is not contraindicated for pregnancy or lactation, but caution should be exercised.' US label (Pregnancy Category C), verbatim: 'There are no adequate and well-controlled studies in pregnant women. Ketoconazole should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. In humans, ketoconazole is not detected in plasma after chronic shampooing on the scalp. Ketoconazole has been shown to be teratogenic (syndactylia and oligodactylia) in the rat when given orally in the diet at 80 mg/kg/day (a dose 10 times the maximum recommended human oral dose). However, these effects may be related to maternal toxicity, which was seen at this and higher dose levels.'

Ketoconazole

Brand names: Nizoral

Ketoconazole is an imidazole antifungal; topical formulations treat skin and scalp fungal infections, while oral ketoconazole is restricted to endogenous Cushing's syndrome owing to hepatotoxicity.

Adult dose

Dose: Ketoconazole 2% w/w shampoo, applied topically. Seborrhoeic dermatitis and dandruff: use twice weekly for 2 to 4 weeks; prophylaxis thereafter once every 1 to 2 weeks. Pityriasis versicolor: use once daily for a maximum of 5 days; for prophylaxis before sun exposure, once daily for a maximum of 3 days in a single treatment course. Method: wet the hair and scalp thoroughly with water, apply sufficient shampoo to produce enough lather to wash the scalp and hair, massage gently over the entire scalp and leave for 3 to 5 minutes before rinsing thoroughly.
Route: Topical — UK SPC §4.2: 'For topical administration.' The US label applies it to 'the damp skin of the affected area and a wide margin surrounding this area'. SCOPE: the 2% shampoo only, which is this page's primary route and indication; the page's secondary ORAL route is not dosed here because no oral label was fetched (see notes).
Frequency: Twice weekly for seborrhoeic dermatitis and dandruff (2 to 4 weeks), then once every 1 to 2 weeks for prophylaxis; once daily for pityriasis versicolor. UK SPC §4.2 covers 'Adults including the elderly and adolescents'.
Max: No maximum quantity per application is stated — the SPC directs 'Apply sufficient shampoo to produce enough lather to wash the scalp and hair'. The highest application frequency anywhere in either fetched label is once daily, and the only explicit 'maximum' is a course-length limit for pityriasis versicolor: 'Use Ketoconazole 2% w/w shampoo once daily for a maximum of 5 days', with 'once daily for a maximum of 3 days in a single treatment course' before sun exposure.
ORAL ketoconazole is NOT dosed here: no oral product was fetched in this bundle. STRENGTH IS PINNED by the product name — 'Ketoconazole 2% w/w Shampoo' — so the application instruction is quantified even though it is not expressed in milligrams. || VERBATIM POSOLOGY (UK SPC §4.2): 'For topical administration. Adults including the elderly and adolescents: Wet hair and scalp thoroughly with water. Apply sufficient shampoo to produce enough lather to wash the scalp and hair, gently massage it over the entire scalp and leave for 3-5 minutes before rinsing thoroughly. Seborrhoeic dermatitis and dandruff: Use Ketoconazole 2% w/w shampoo twice weekly for 2-4 weeks. Prophylaxis: Use Ketoconazole 2% w/w shampoo once every 1-2 weeks. Pityriasis versicolor: Use Ketoconazole 2% w/w shampoo once daily for a maximum of 5 days. Prophylaxis: As patches of pityriasis versicolor become more apparent on exposure to the sun. Ketoconazole 2% w/w shampoo may be used once daily for a maximum of 3 days in a single treatment course before exposure to sunshine.' || US label (cross-check, tinea versicolor wording): 'Apply the shampoo to the damp skin of the affected area and a wide margin surrounding this area. Lather, leave in place for 5 minutes, and then rinse off with water. One application of the shampoo should be sufficient.' Note this differs from the UK SPC's up-to-5-day pityriasis versicolor course; the UK SPC wording is what is published above. || CORTICOSTEROID WITHDRAWAL (§4.4): 'In patients who have been on prolonged treatment with topical corticosteroids, it is recommended that the steroid therapy be gradually withdrawn over a period of 2 – 3 weeks, while using Ketoconazole 2% w/w shampoo, to prevent any potential rebound effect.' || EYES (§4.4): 'Ketoconazole 2% w/w shampoo may be irritating to mucous membranes of the eyes and contact with this area should be avoided. If Ketoconazole 2% w/w shampoo does get into the eyes, they should be bathed gently with cold water.' || EXCIPIENT (§4.4): 'This medicine contains 5.00 mg benzyl alcohol in each g which is equivalent to 0.50 % w/w. Benzyl alcohol may cause allergic reactions and mild local irritation.' || INTERACTIONS (§4.5): 'No interaction studies have been performed.' || PAEDIATRIC (why paedDose is null): the SPC posology heading covers 'Adults including the elderly and adolescents' and gives no separate paediatric regimen or weight-based dose; the US label states 'Safety and effectiveness in children have not been established.' Verify any paediatric use against a children's formulary.

Dose adjustments

Renal

Not stated — no renal-impairment statement appears in either fetched label for the 2% shampoo. Both note negligible systemic exposure: UK SPC §4.6 'Ketoconazole 2% w/w shampoo is not detected in plasma after chronic shampooing or topical application'; US label 'In humans, ketoconazole is not detected in plasma after chronic shampooing on the scalp.'

Hepatic

Not stated for the 2% shampoo in either fetched label. CAUTION: the hepatotoxicity that restricts ORAL ketoconazole is not addressed by these topical labels, and no oral ketoconazole label was fetched in this bundle — nothing here can be used to dose, permit or contraindicate oral ketoconazole in liver disease.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity — UK SPC §4.3, verbatim and in full: 'Hypersensitivity to ketoconazole or any of the excipients.' US label: 'Ketoconazole shampoo, 2% is contraindicated in persons who have known hypersensitivity to the active ingredient or excipients of this formulation.'
  • Not a contraindication but a §4.4 precaution: 'Ketoconazole 2% w/w shampoo may be irritating to mucous membranes of the eyes and contact with this area should be avoided.'

Side effects

  • UK SPC §4.8, overall: 'The safety of Ketoconazole 2% Shampoo was evaluated in 2980 subjects who participated in 22 clinical trials... Based on pooled safety data from these clinical trials, there were no ADRs reported with an incidence ≥ 1%.'
  • Uncommon (≥1/1,000 and <1/100): folliculitis; increased lacrimation; alopecia, dry skin, abnormal hair texture; application site erythema, application site irritation, application site pruritus, application site reaction
  • Rare (≥1/10,000 and <1/1,000): dysgeusia; eye irritation; rash, skin burning sensation, acne, dermatitis contact, skin disorder, skin exfoliation; application site hypersensitivity, application site pustules
  • Not known: hypersensitivity; angioedema, urticaria, hair colour changes
  • US label: 'In 11 double-blind trials in 264 patients using ketoconazole shampoo, 2% for the treatment of dandruff or seborrheic dermatitis, an increase in normal hair loss and irritation occurred in less than 1% of patients.' In open-label safety trials 'abnormal hair texture, scalp pustules, mild dryness of the skin, and itching' each occurred once, and 'As with other shampoos, oiliness and dryness of hair and scalp have been reported.'
  • Benzyl alcohol excipient (§4.4): 'Benzyl alcohol may cause allergic reactions and mild local irritation.'

Monitoring

  • No laboratory or clinical monitoring is specified for the 2% shampoo in either fetched label, and UK SPC §4.5 states 'No interaction studies have been performed'.
  • Observe during use — UK SPC §4.4: 'In patients who have been on prolonged treatment with topical corticosteroids, it is recommended that the steroid therapy be gradually withdrawn over a period of 2 – 3 weeks, while using Ketoconazole 2% w/w shampoo, to prevent any potential rebound effect.'

Clinical monograph

How it works

It inhibits fungal cytochrome P450 14-alpha-demethylase to impair ergosterol synthesis; at higher systemic exposure it also inhibits steroidogenic enzymes, underpinning its use in Cushing's syndrome.

Prescribing in practice

  • Systemic ketoconazole carries a risk of serious, potentially fatal hepatotoxicity, so oral use for fungal infection is no longer authorised and it is reserved for Cushing's syndrome under specialist care.
  • It is a potent CYP3A4 inhibitor with numerous, sometimes serious, drug interactions including QT-prolonging agents.
  • Topical preparations have minimal systemic absorption and a favourable safety profile.

Monitoring

For oral therapy, monitor liver function before and regularly during treatment and review for drug interactions; topical use needs no routine monitoring.

Counselling the patient

  • For shampoo or cream, apply as directed and avoid contact with the eyes.
  • If taking tablets, report nausea, vomiting, abdominal pain, jaundice or dark urine immediately.
  • Tell your clinician about all other medicines because of important interactions.

Evidence & guidelines

The European medicines review withdrew authorisation of oral ketoconazole for fungal infections because hepatotoxicity risk outweighed benefit; see MHRA guidance.

Reference: MHRA Drug Safety Update 2013; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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