Version July 2025
General dosing:
Microsize: Infants, Children, and Adolescents: Limited data available in ages ≤2 years: Oral: 20 to 25 mg/kg/day as a single daily dose or divided twice daily; maximum daily dose: 1,000 mg/day (Ref).
Ultramicrosize: Children >2 years and Adolescents: Oral: 10 to 15 mg/kg/day once daily; maximum daily dose: 750 mg/day (Ref).
Tinea capitis (scalp ringworm):
Microsize:
Infants, Children, and Adolescents: Limited data available in ages ≤2 years: Oral: 20 to 25 mg/kg/day in a single daily dose or in 2 divided doses; maximum daily dose: 1,000 mg/day; for 6 to 12 weeks until clinical resolution (Ref). Although the manufacturer recommends lower doses (10 mg/kg/day), they are associated with need for extended treatment durations and/or potentially lower cure rates (Ref).
Ultramicrosize:
Children >2 years and Adolescents: Oral: 10 to 15 mg/kg/day in a single daily dose or in 2 divided doses; maximum daily dose: 750 mg/day; for 6 to 12 weeks until clinical resolution (Ref).
Tinea corporis (ringworm), tinea cruris (jock itch), and tinea pedis (athlete's foot) (alternative agent): Note: Dosing is extrapolated from tinea capitis; oral therapy should be reserved for disease that does not respond to topical therapy or for extensive/severe infection (Ref).
Microsize: Infants, Children, and Adolescents: Limited data available in ages ≤2 years: Oral: 10 to 25 mg/kg/day in a single daily dose or in 2 divided doses; maximum daily dose: 1,000 mg/day (Ref).
Ultramicrosize: Children >2 years and Adolescents: Oral: 5 to 15 mg/kg/day in a single dose or in 2 divided doses; maximum daily dose: 750 mg/day (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling.
Use is contraindicated in liver failure.
(For additional information see "Griseofulvin: Drug information")
Onychomycosis ( alternative agent):
Note: Reserve for patients unable to use preferred agents due to the increased risk for adverse effects, reduced efficacy, and need for prolonged treatment duration with griseofulvin (Ref).
Microsize: Oral: 1 g/day in single or divided doses (Ref).
Ultramicrosize:
125 and 250 mg tablet: Oral: 750 mg/day in single or divided doses (Ref).
165 mg tablet: Oral: 660 mg/day in divided doses.
Duration: >4 months (eg, 6 to 9 months) for fingernail and >6 months (eg, 12 to 18 months) for toenail infection (Ref).
Tinea infection:
Dermatophyte folliculitis (tinea barbae, Majocchi granuloma) (alternative agent):
Microsize: Oral: 500 mg/day in single or divided doses (Ref).
Ultramicrosize:
125 and 250 mg tablet: Oral: 375 mg/day in single or divided doses.
165 mg tablet: Oral: 330 mg/day in single or divided doses.
Duration: 4 to 8 weeks or until clinical resolution (Ref).
Tinea capitis:
Microsize: Oral: 500 mg to 1 g/day in single or divided doses (Ref).
Ultramicrosize:
125 and 250 mg tablet: Oral: 375 to 750 mg/day in single or divided doses (Ref).
165 mg tablet: Oral: 330 mg/day in single or divided doses.
Duration: 4 to 6 weeks according to the manufacturer's labeling, but based on experience in pediatrics, up to 12 weeks may be required (Ref).
Tinea corporis/Tinea cruris:
Note: For disease that is extensive or refractory to topical therapy (Ref).
Microsize: Oral: 500 mg to 1 g/day in single or divided doses (Ref).
Ultramicrosize:
125 and 250 mg tablet: Oral: 375 to 500 mg/day in single or divided doses (Ref).
165 mg tablet: Oral: 330 mg/day in single or divided doses.
Duration: 2 to 4 weeks (Ref).
Tinea pedis (labeled use)/Tinea manuum (off-label use):
Note: For disease that is extensive or refractory to topical therapy (Ref).
Microsize: Oral: 1 g/day in single or divided doses (Ref).
Ultramicrosize:
125 and 250 mg tablet: Oral: 750 mg/day in divided doses (Ref).
165 mg tablet (tinea pedis only): Oral: 660 mg/day in divided doses.
Duration: 4 to 8 weeks (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling.
Use is contraindicated in hepatic failure.
The following adverse drug reactions are derived from product labeling unless otherwise specified.
Postmarketing:
Dermatologic: Erythema multiforme (Hidajat 2014), severe dermatological reaction (including Stevens-Johnson syndrome, toxic epidermal necrolysis) (Araujo 1990), skin photosensitivity (Araujo 1990)
Endocrine & metabolic: Porphyria (Araujo 1990)
Gastrointestinal: Abdominal cramps (Araujo 1990), anorexia (Araujo 1990), diarrhea (Araujo 1990), epigastric discomfort, flatulence (Araujo 1990), gastrointestinal hemorrhage, nausea (Araujo 1990), oral candidiasis, vomiting (Araujo 1990)
Genitourinary: Proteinuria (Bhat 2016)
Hematologic & oncologic: Disorder of hemostatic components of blood, leukopenia
Hepatic: Hepatitis, hepatotoxicity, hyperbilirubinemia, increased serum alanine aminotransferase, increased serum aspartate aminotransferase, jaundice
Hypersensitivity: Angioedema, drug reaction with eosinophilia and systemic symptoms (Maiolo 2016), hypersensitivity reaction (Quero 1960), serum sickness (Araujo 1990)
Nervous system: Confusion, dizziness (Araujo 1990), fatigue (Araujo 1990), headache (Araujo 1990), insomnia (Araujo 1990), paresthesia, peripheral neuropathy
Neuromuscular & skeletal: Exacerbation of systemic lupus erythematosus (Madhok 1985), lupus erythematosus, lupus-like syndrome
Renal: Acute kidney injury (Bhat 2016), nephrosis
Hypersensitivity to griseofulvin or any component of the formulation; hepatic failure; porphyria; pregnancy
Concerns related to adverse effects:
• Hematologic effects: Leukopenia has been reported (rare); discontinue therapy if granulocytopenia occurs.
• Hepatic effects: May cause jaundice and elevated liver function tests or bilirubin (may be serious or even fatal); monitor hepatic function and discontinue therapy if necessary.
• Penicillin allergy: Hypersensitivity cross reaction between penicillins and griseofulvin is possible, however, known penicillin-sensitive patients have been treated successfully without complications.
• Photosensitivity: Avoid exposure to intense sunlight to prevent photosensitivity reactions.
• Skin reactions: Severe skin reactions (eg, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme) have been reported (may be serious or even fatal); discontinue use if severe skin reactions occur.
Disease-related concerns:
• Lupus erythematosus: Development of lupus erythematosus, lupus-like syndromes or exacerbation of existing lupus erythematosus has been reported.
Other warnings/precautions:
• Appropriate use: Use for the prophylaxis of fungal infections has not been established; not effective for the treatment of tinea versicolor (pityriasis versicolor).
Microsized formulations: 500 mg tablet and suspension.
Ultramicrosize formulation: 125 mg, 165 mg, and 250 mg tablets.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Suspension, Oral:
Generic: 125 mg/5 mL (118 mL, 120 mL)
Tablet, Oral:
Fulvicin P/G 165: 165 mg [scored; contains corn starch]
Generic: 125 mg, 165 mg, 250 mg, 500 mg
Yes
Suspension (Griseofulvin Microsize Oral)
125 mg/5 mL (per mL): $0.65 - $2.50
Tablets (Griseofulvin Microsize Oral)
500 mg (per each): $8.80 - $9.35
Tablets (Griseofulvin Ultramicrosize Oral)
125 mg (per each): $4.69 - $4.99
165 mg (per each): $39.68
250 mg (per each): $6.00 - $6.37
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Oral:
Microsize oral suspension: Administer with fatty food to increase absorption (Ref). Shake suspension well before use. Administer with an accurate measuring device (calibrated oral syringe or measuring cup); do not use a household teaspoon or tablespoon to measure dose (overdosage may occur).
Microsize tablets: Administer with fatty food to increase absorption (Ref).
Ultramicrosize tablets: Administer with fatty food to increase absorption (Ref). Swallow whole; alternatively, 125 and 250 mg tablets may be crushed and sprinkled onto 1 tablespoonful of applesauce and swallowed immediately without chewing.
Oral: Administer with fatty food to increase absorption (Ref).
Additional formulation-specific administration information:
Ultramicrosize formulation (125 mg and 250 mg tablets): May be swallowed whole or crushed and sprinkled onto 1 tablespoonful of applesauce and swallowed immediately without chewing.
Suspension: Shake well before use.
Store at 20°C to 25°C (68°F to 77°F). Protect from light.
Treatment of the following tinea infections caused by susceptible species of Microsporum, Epidermophyton, or Trichophyton when lesions are unresponsive to topical antifungal therapy: tinea corporis, tinea pedis, tinea cruris, tinea barbae, tinea capitis, and tinea unguium (FDA approved in ages >2 years and adults).
Note: Although FDA approved for tinea unguium, griseofulvin is no longer routinely recommended for pediatric patients for this indication due to higher rate of adverse effects, prolonged treatment duration, and lower efficacy than other agents (Ameen 2014; Kreijkamp-Kaspers 2017; Red Book [AAP 2024]).
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drugs (contraindicated in pregnancy) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Community/Ambulatory Care Settings).
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program
Alcohol (Ethyl): Griseofulvin may increase adverse/toxic effects of Alcohol (Ethyl). A disulfiram-like reaction may occur. Risk C: Monitor
Aminolevulinic Acid (Systemic): Photosensitizing Agents may increase photosensitizing effects of Aminolevulinic Acid (Systemic). Risk X: Avoid
Aminolevulinic Acid (Topical): Photosensitizing Agents may increase photosensitizing effects of Aminolevulinic Acid (Topical). Risk C: Monitor
Barbiturates: May decrease serum concentration of Griseofulvin. Risk C: Monitor
Chlorprothixene: Griseofulvin may increase adverse/toxic effects of Chlorprothixene. Specifically, the risk for acute porphyrias may be increased. Risk C: Monitor
CycloSPORINE (Systemic): Griseofulvin may decrease serum concentration of CycloSPORINE (Systemic). Risk C: Monitor
Hormonal Contraceptives: Griseofulvin may decrease serum concentration of Hormonal Contraceptives. Management: Advise patients to use an alternative method of contraception or a back-up method during coadministration, and to continue back-up contraception for 28 days after discontinuing griseofulvin to ensure contraceptive reliability. Risk D: Consider Therapy Modification
Methoxsalen (Systemic): Photosensitizing Agents may increase photosensitizing effects of Methoxsalen (Systemic). Risk C: Monitor
Porfimer: Photosensitizing Agents may increase photosensitizing effects of Porfimer. Risk X: Avoid
Saccharomyces boulardii: Antifungal Agents (Systemic and Oral [Non-Absorbable]) may decrease therapeutic effects of Saccharomyces boulardii. Risk X: Avoid
Ulipristal: Griseofulvin may decrease serum concentration of Ulipristal. Risk X: Avoid
Verteporfin: Photosensitizing Agents may increase photosensitizing effects of Verteporfin. Risk C: Monitor
Vitamin K Antagonists: Griseofulvin may decrease serum concentration of Vitamin K Antagonists. Risk C: Monitor
Ethanol: Concomitant ethanol use may cause rare disulfiram reaction. Management: Monitor patients.
Food: Griseofulvin concentrations may be increased if taken with food, especially with high-fat meals. Management: Take with a fatty meal (peanuts or ice cream) to increase absorption, or with food or milk to avoid GI upset.
Females of reproductive potential should use affective contraception during therapy (estrogen containing contraceptives may be less effective). Men should avoid fathering a child for at least 6 months after therapy.
Griseofulvin crosses the placenta (Pacifici 2006). Adverse events have been observed in humans (two cases of conjoined twins); therefore, use during pregnancy is contraindicated.
Liver function (AST, ALT, bilirubin) if treatment duration >8 weeks (Red Book [AAP 2024]); signs of hepatotoxicity with prolonged use (Ely 2014); CBC (periodically).
Inhibits fungal cell mitosis at metaphase; binds to human keratin making it resistant to fungal invasion
Absorption: Ultramicrosize griseofulvin absorption is almost complete; absorption of microsize griseofulvin is variable (27% to 72% of an oral dose); enhanced by ingestion of a fatty meal (GI absorption of ultramicrosize is ~1.5 times that of microsize); absorbed from the duodenum
Distribution: Deposited in the keratin layer of skin, hair, and nails; concentrates in liver, fat, and skeletal muscles; Vd: ~1.5 L (Vozeh 1988)
Metabolism: Extensively hepatic
Half-life elimination: 9 to 24 hours
Time to peak, serum: 4 hours
Excretion: Urine (<1% as unchanged drug); feces (~33%); perspiration
