COMMON INITIAL DOSING REGIMENS

• Apply approximately 1 mL of 0.1%–0.25% topical finasteride solution to the affected scalp area once daily. Specific concentrations and formulations may vary depending on the compounding pharmacy and provider recommendations.

MECHANISM OF ACTION

• Finasteride is a selective inhibitor of type II 5-alpha-reductase, an enzyme that converts testosterone into dihydrotestosterone (DHT). DHT is a key factor in the miniaturization of hair follicles and the progression of androgenetic alopecia. By reducing DHT levels in the scalp, finasteride prevents further hair follicle shrinkage and supports the regrowth of terminal hairs. Topical administration localizes the effect to the scalp, reducing systemic DHT suppression compared to oral formulations.

COMMON SIDE EFFECTS

• Topical: Localized irritation, redness, and itching of the scalp may occur, especially in formulations with alcohol or other irritating excipients.

• Systemic Absorption: Although significantly less common than with oral finasteride, systemic absorption can lead to side effects such as reduced libido, erectile dysfunction, gynecomastia, or mood changes. These effects are reported to be rare with proper use of topical formulations.

• Other: Hair shedding may temporarily increase during the first few months as follicles transition to the anagen (growth) phase.

CONTRAINDICATIONS

• Absolute: Hypersensitivity to finasteride or any excipient in the formulation. Pregnant or potentially pregnant women should not handle finasteride-containing products due to the risk of absorption and potential harm to a male fetus.

• Relative: Patients with significant scalp irritation or broken skin should use topical finasteride cautiously to avoid increased systemic absorption. Use in women for androgenetic alopecia remains off-label and requires careful consideration.

ADDITIONAL NOTES ON EFFICACY

• Topical finasteride has been shown to reduce DHT levels in the scalp effectively while maintaining near-normal systemic DHT levels, thus lowering the risk of systemic side effects. Combining topical finasteride with minoxidil can enhance hair regrowth outcomes. Clinical response typically begins after 3–6 months of consistent application.

MORE INFORMATION

• FDA Safety Data Sheet for oral finasteride may be found here.

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• Keerti A. Topical Finasteride: A Comprehensive Review of Androgenetic Alopecia Management for Men and Women. Cureus. 2023 [PubMed link]

• Gupta AK. Topical finasteride for male and female pattern hair loss: Is it a safe and effective alternative?. J Cosmet Dermatol. 2022 [PubMed link]

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• Devjani S. Androgenetic Alopecia: Therapy Update. Drugs. 2023 [PubMed link]

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• Suchonwanit P. A randomized, double-blind controlled study of the efficacy and safety of topical solution of 0.25% finasteride admixed with 3% minoxidil vs. 3% minoxidil solution in the treatment of male androgenetic alopecia. J Eur Acad Dermatol Venereol. 2018 [PubMed link]

• Caserini M. Effects of a novel finasteride 0.25% topical solution on scalp and serum dihydrotestosterone in healthy men with androgenetic alopecia. Int J Clin Pharmacol Ther. 2016 [PubMed link]

• Rossi A. Efficacy of the association of topical minoxidil and topical finasteride compared to their use in monotherapy in men with androgenetic alopecia: A prospective, randomized, controlled, assessor blinded, 3-arm, pilot trial. J Cosmet Dermatol. 2024 [PubMed link]