Antifungal (oral) Pregnancy: No evidence of safety in human pregnancy; teratogenic in animals and case reports of human foetal abnormalities. Must not be used in pregnancy or become pregnant within one month of stopping; males should not father children within six months of treatment. Excretion in human milk unknown.

Griseofulvin

Brand names: Grisol

Griseofulvin is an oral antifungal used for dermatophyte (ringworm) infections of the skin, hair and nails that are unresponsive to topical treatment.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 500 to 1000 mg daily (but not less than 10 mg/kg bodyweight daily)

Route: Oral

Frequency: A single dose daily is often satisfactory, but divided doses may be more effective in patients who respond poorly

For dermatophyte (ringworm) infections of skin, hair and nails. Duration depends on thickness of keratin at the site of infection: for hair or skin at least four weeks; toe or fingernails may need six to twelve months. Therapy should be continued for at least two weeks after all signs of infection have disappeared. Doses should be taken after meals, otherwise absorption is likely to be inadequate. Should not be used prophylactically.

Paediatric dose

Dose: 10 mg/kg

Route: Oral

Frequency: Daily in divided doses

eMC (UK SPC) paediatric population: usually 10 mg/kg (5 mg/lb) body weight daily in divided doses. Doses should be taken after meals. Duration as for adults (skin/hair at least four weeks; nails six to twelve months; continue at least two weeks after signs of infection disappear).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Porphyria or severe liver disease
Systemic Lupus Erythematosus (griseofulvin has been reported to exacerbate the condition)
Hypersensitivity to the active substance or to any of the excipients
Pregnancy, or women intending to become pregnant within one month of stopping treatment; males should not father children within six months of treatment

Side effects

Diarrhoea, nausea and vomiting (common)
Headache and gastric discomfort
Urticarial reactions, skin rashes; photosensitivity reactions
CNS effects e.g. confusion, dizziness, impaired coordination, peripheral neuropathy; drowsiness
Rare: toxic epidermal necrolysis, erythema multiforme, significant LFT elevations, leucopenia with neutropenia, precipitation of SLE

Interactions

Oral contraceptives: reduced blood level/efficacy — additional contraceptive precautions needed during treatment and for a month after stopping
Coumarin anticoagulants: reduced efficacy — monitor and adjust dose
Cyclosporin: reduced blood level/efficacy
Phenobarbitone: inhibits absorption of griseofulvin; phenylbutazone and sedative/hypnotic enzyme-inducing drugs may impair griseofulvin efficacy
Alcohol: enhancement of the effects of alcohol has been reported

Clinical monograph

How it works

It interferes with fungal microtubule function and mitotic spindle formation, inhibiting fungal cell division, and is deposited in keratin so that newly formed skin, hair and nail become resistant to dermatophyte invasion.

Prescribing in practice

It is contraindicated in pregnancy and in severe liver disease, and effective contraception is advised during and for a period after treatment in both women and men as per current prescribing references.
It induces hepatic enzymes and can reduce the efficacy of combined hormonal contraceptives, warfarin and other interacting drugs.
Treatment is often prolonged, especially for hair and nail infections, and absorption is improved when taken with fatty food.

Monitoring

For prolonged courses monitor liver function and blood counts, and review treatment response clinically with appropriate mycological confirmation.

Counselling the patient

Take the full course, which may last several weeks or months for nail and scalp infections.
Avoid alcohol, and report yellowing of the skin or eyes or persistent nausea.
Use additional or alternative contraception as advised, as this medicine can make the contraceptive pill less reliable.

Evidence & guidelines

Griseofulvin is a long-established systemic treatment for dermatophyte infections, particularly tinea capitis, and remains recommended where topical therapy is inadequate.

Reference: NICE CKS; 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).

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