Sir,

Isotretinoin remains a cornerstone systemic retinoid in the management of moderate to severe acne, offering durable remission through sebosuppression and keratinization-normalizing and anti-inflammatory effects. While its adverse effect profile is well established, paradoxical or atypical cutaneous reactions continue to emerge. Among these, isotretinoin-induced hirsutism represents an exceedingly uncommon and poorly characterized event, typically occurring in women without biochemical evidence of androgen excess. Conversely, isotretinoin has been reported to improve seborrheic dermatitis by modulating sebaceous gland activity and altering the cutaneous microenvironment. The simultaneous occurrence of these opposing outcomes in a single patient highlights the complex and, at times, contradictory cutaneous action of isotretinoin. Herein, we report a distinctive case in which isotretinoin therapy precipitated facial hirsutism while inducing the complete remission of chronic seborrheic dermatitis.

A woman in her mid-20s with a five-year history of moderate, persistent acne unresponsive to topical and oral therapies was initiated on isotretinoin 30 mg daily. Supportive measures included sunscreen and emollients.

By the third month of therapy, she developed coarse terminal hair on the chin and jawline (Ferriman–Gallwey score increased from 2 to 7), without other features of virilization. Menstrual cycles remained regular. Laboratory investigations, including LH, FSH, and TSH, were normal. Pelvic ultrasound revealed normal ovarian morphology.

At the same time, her chronic seborrheic dermatitis of the scalp, previously refractory to ketoconazole and zinc pyrithione shampoos, resolved completely.

Isotretinoin was continued for eight months, resulting in near-complete clearance of the acne. Following discontinuation, hirsutism regressed within two months and resolved by the third month. Seborrheic dermatitis remained in remission throughout one year of follow-up.

Because of cultural restrictions, clinical photographs were not obtained. All clinical findings were confirmed by serial in-person dermatological assessments. Table 1 summarizes the clinical course.

Table 1: Clinical timeline.

This case illustrates the paradoxical dual effects of isotretinoin: induction of facial hirsutism and remission of seborrheic dermatitis.

Isotretinoin-induced hirsutism is rarely reported. Ramot et al. described severe facial hirsutism in a normoandrogenic woman, suggesting a localized follicular effect independent of systemic androgen excess [1]. Similar observations have been made in adolescents, where isotretinoin was associated with unexpected hormonal and cutaneous changes [2,3]. Aktar et al. further demonstrated increased Ferriman–Gallwey scores and menstrual irregularities despite stable pituitary and adrenal profiles, highlighting the individualized nature of isotretinoin’s endocrine actions [3]. Its reported benefit in hyperandrogenic patients with polycystic ovary syndrome supports the view that baseline hormonal status influences these outcomes [4].

The resolution of seborrheic dermatitis observed in this case aligns with previous studies demonstrating that isotretinoin reduces sebum secretion and disrupts the lipid-rich environment necessary for Malassezia proliferation [5–7]. Although it does not eradicate Malassezia, this reduction in microbial growth and inflammation may result in long-term remission.

Taken together, these findings emphasize the complex and sometimes contradictory effects of isotretinoin. Clinicians should be aware of such unusual responses to ensure appropriate monitoring, counseling, and recognition of potential therapeutic benefits.

Isotretinoin may paradoxically induce facial hirsutism in normoandrogenic women while simultaneously inducing a remission of seborrheic dermatitis. Awareness of these unusual effects is important for patient counseling and monitoring during therapy.

REFERENCES

1.Ramot Y, Sheffer S, Zlotogorski A. Severe facial hirsutism following isotretinoin therapy:An under-reported entity. Int J Trichology. 2015;7:129-30.

2.Akpolat D. Unexpected effects of oral isotretinoin in adolescents with acne vulgaris. Cureus. 2021;13:e17115.

3.Aktar R, Gunes Bilgili S, Yavuz IH, Ozaydin Yavuz G, Aktar S, Ozturk M, et al. Evaluation of hirsutism and hormonal parameters in acne vulgaris patients treated with isotretinoin. Int J Clin Pract. 2021;75:e13791.

4.Elnagar HI, Hashem OA, Aboelwafa HO, Elhelw E, Elsaie ML. The impact of oral isotretinoin on ovarian functions of acne patients complaining of polycystic ovarian syndrome:A prospective study. J Ovarian Res. 2024;17:21.

5.Gualtieri B, Panduri S, Chiricozzi A, Romanelli M. Improvement of seborrheic dermatitis with low-dose isotretinoin. G Ital Dermatol Venereol. 2020;155:685-6.

6.de Souza Leão Kamamoto C, Sanudo A, Hassun KM, Bagatin E. Low-dose isotretinoin for seborrhea and seborrheic dermatitis. Int J Dermatol. 2017;56:80-85.

7.Gaitanis G, Magiatis P, Hantschke M, Bassukas ID, Velegraki A. The Malassezia genus in skin and systemic diseases. Clin Microbiol Rev. 2012;25:106-41.