Disclaimer (02/20/2026):
This paper was written for an individual in need - he is described below. It was meant to be read by his physician, not community members. However, I intend on cataloguing my research, so this will be published as well. This paper relies heavy on quotes and external sources.
5a-reductase Inhibitors as a Treatment Option for Hidradenitis Suppurativa
Authored by Kolvas Kaaz
Original draft: Jul 26, 2024
Regarding the case of an adult male with moderate to severe hidradenitis suppurativa, estradiol and anti-androgen therapy may not be necessary. Instead, consider using an oral 5α-reductase inhibitor to reduce systemic levels of DHT, which would have anti-androgenic effects on the patient’s hair follicles and skin. Studies have supported oral 5α-reductase inhibitor use for HS at a dosage of 5mg/day for finasteride, with noted improvement of symptoms: “The dose of finasteride was 5mg/day, and no side effects were noted after the duration of nine months and three months, respectively, with dramatic improvement of HS.” (Khandalavala, et al). Additionally, “Finasteride 5 mg daily … has been reported as an effective HS treatment,” “Finasteride was used effectively in a study as monotherapy (5 mg/d) in 7 patients. Six patients showed significant improvement and 3 patients demonstrated complete healing,“ (Scheinfeld, Noah). Dutasteride, on the other hand, may prove to be a better choice if symptoms do not significantly improve with finasteride. Dutasteride differs from finasteride in that it “...blocks DTH-2 isoenzyme (more so than finasteride) and the DTH-1 isoenzyme, which finasteride does not block … DHT-1 is most active in the skin.” (Scheinfeld, Noah). However, the potential side effects of dutasteride may outweigh the benefits over finasteride for some patients. Therefore, this paper will focus more on finasteride as opposed to dutasteride therapy.
Dihydrotestosterone is a potent androgen that “...promotes prostate growth, sebaceous gland activity, male pattern baldness, and body, facial, and pubic hair growth.” (Kinter, Kevin J). Additionally, “DHT is significantly more potent than the other androgens … Compared to testosterone, DHT has approximately double the binding affinity to the androgen receptor and a dissociation rate about five times slower…” “DHT is … the primary androgen responsible for facial hair, body hair, pubic hair, and prostate growth.” By reducing serum levels of dihydrotestosterone, body, facial and pubic hair, as well as sebaceous gland activity, would all experience a marked reduction in masculine physiology.
Regarding the efficacy of finasteride in reducing DHT levels, “In two 1-year trials, 1553 men (18 to 41 years of age) with male pattern hair loss received oral finasteride 1 mg/d or placebo…” The findings: “Finasteride markedly reduced serum DHT from a median of 44.0 ng/dL at baseline (normal range = 30-85 ng/dL) to 14.0 ng/dL at month 12 (median percent change ± SE = –68.4% ± 1.2%; P < .001 vs placebo)” (Kaufman, et al).
Administering systemic finasteride once a day, every day, would reduce systemic levels of DHT, having anti-androgenic effects in the skin and hair follicles, without the inevitability of breast growth, gynoid fat redistribution, and other feminizing effects which accompany joint anti-androgen and estradiol therapy. To gain better insight as to how low levels of DHT affect a man, we can look at cases of individuals with 5a-reductase 2 deficiency. For example, in “Steroid 5α-reductase 2 deficiency” published in The Journal of Steroid Biochemistry and Molecular Biology, it is said of the males affected with 5a-reductase deficiency that: “At puberty, deepening of the voice, development of muscle mass and virilization of external genitalia occur,” and that “Gynecomastia is only rarely observed in males with 5a-reductase type 2 deficiency, a feature that is in contrast to the findings in partial androgen insensitivity syndrome,” (Mendonca, et al). In addition, it is stated that “Many subjects … with androgen insensitivity or androgen deficiency develop osteopenia/osteoporosis, but two studies suggest that the majority of men with 5a-reductase type 2 deficiency have normal bone density.” Such findings support the use of 5a-reductase inhibitors as opposed to testosterone blockers in cases pertaining to the effects of dihydrotestosterone. Currently, a regiment of low dose estradiol and flutamide has anti-androgenic effects on the patient’s skin and hair follicles. However, as previously mentioned, this treatment approach will induce physical, mental, emotional and sexual changes, which may cause distress and social challenges. Systemic 5a-reductase inhibitor therapy would allow for similar anti-androgenic effects on the patient’s skin and hair follicles, without inducing feminization. These medications would also refrain from causing osteoporosis as found in anti-androgen therapy, therefore not necessitating estradiol supplementation.
Works Cited:
- Khandalavala, Birgit N, and Melissa Voutsalath Do. “Finasteride in Hidradenitis Suppurativa: A ‘Male’ Therapy for a Predominantly ‘Female’ Disease.” The Journal of Clinical and Aesthetic Dermatology, U.S. National Library of Medicine, June 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC4928456/.
- Scheinfeld, Noah. “Hidradenitis suppurativa: A practical review of possible medical treatments based on over 350 hidradenitis patients.” Dermatology Online Journal, vol. 19, no. 4, 1 Apr. 2013, https://doi.org/10.5070/d35vw402nf.
- Kinter, Kevin J. “Biochemistry, Dihydrotestosterone.” StatPearls [Internet]., U.S. National Library of Medicine, 30 July 2023, www.ncbi.nlm.nih.gov/books/NBK557634/.
- Kaufman, Keith D., et al. “Finasteride in the treatment of men with Androgenetic Alopecia.” Journal of the American Academy of Dermatology, vol. 39, no. 4, Oct. 1998, pp. 578–589, https://doi.org/10.1016/s0190-9622(98)70007-6.
- Mendonca, Berenice B., et al. “Steroid 5α-reductase 2 deficiency.” The Journal of Steroid Biochemistry and Molecular Biology, vol. 163, Oct. 2016, pp. 206–211, https://doi.org/10.1016/j.jsbmb.2016.05.020.
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