A 44-year-old man with androgenetic alopecia (Fig. 1a) underwent hair transplantation. Following a satisfactory result (Fig. 1b), 12 months later we performed a session of 0.05% dutasteride mesotherapy in an alcohol-based solution. During the session, the patient complained of intense pain, which persisted during the following days. Two weeks after treatment, the patient attended our clinic because of intense hair shedding, revealing a large alopecic area extending throughout the infiltrated region (Fig. 1c).

Fig. 1.

Patient #1: (a) advanced androgenetic alopecia before hair transplantation; (b) 12 months after hair transplantation; (c) anagen effluvium 3 weeks after dutasteride mesotherapy; (d) resolved effluvium 4 months after the episode.

A 36-year-old man with androgenetic alopecia (Fig. 2a) underwent hair transplantation (Fig. 2b), and 10 months later received a session of 0.05% dutasteride mesotherapy in an alcohol-based solution, producing notable pain during treatment and throughout the following 24h. Four weeks into therapy, the patient consulted for excessive hair shedding, as well as loss of density throughout the treated area (Fig. 2c). Trichoscopy revealed generally poor density with multiple regrowing vellus hairs and isolated dystrophic hairs (Fig. 2d).

Fig. 2.

Patient #2: (a) advanced androgenetic alopecia before hair transplantation; (b) 10 months after hair transplantation; (c) anagen effluvium 4 weeks after dutasteride mesotherapy; (d) trichoscopic image showing generally poor density with multiple regrowing vellus hairs (red dots) and isolated dystrophic hairs (green dot); (e) resolved effluvium after 3 months.

A 37-year-old woman attended our clinic because of massive hair shedding during the previous 4 weeks, which had produced a striking alopecic area with geographic morphology involving the frontal two-thirds of the scalp (Fig. 3a). During the past medical history interview, the patient reported having undergone dutasteride mesotherapy treatment 6 weeks earlier, which had caused intense pain lasting several days. Trichoscopy revealed generally poor density and a combination of vellus hairs, dystrophic hairs, pigtail hairs, and tulip-shaped hairs (Fig. 3b).

Fig. 3.

Patient #3: (a) anagen effluvium involving the entire frontal and interparietal region 3 weeks after undergoing dutasteride mesotherapy; (b) trichoscopic image showing generally poor density and a combination of vellus hairs (red dots), dystrophic hairs (green dots), pigtail hairs (yellow dot), and tulip-shaped hairs (blue dots); (c) resolved effluvium after 4 months.

All 3 cases were considered secondary anagen effluvium associated with dutasteride mesotherapy treatment, and observation without active treatment was agreed upon. In all 3 cases, spontaneous resolution occurred with complete repopulation between 4 and 6 months later.

Anagen effluvium is considered a form of non-scarring alopecia caused by direct aggression to the hair follicle, affecting its mitotic or metabolic activity and producing massive shedding of hair in the anagen phase. This condition differs mainly from telogen effluvium because of its extent (it may affect up to 90% of scalp hair) and the rapidity with which it develops, potentially beginning during the first week after exposure to the causative agent. Classically, anagen effluvium has been associated with chemotherapy treatments. However, other possible triggers exist, including other drugs, radiotherapy, heavy metal poisoning, or certain inflammatory diseases.4

The development of alopecia due to scalp mesotherapy procedures is a rare adverse effect and only vaguely reflected in the literature. The appearance of inflammatory alopecic plaques at injection sites after administration of a combined multivitamin solution has been described. These cases presented as patchy alopecia with inflammatory infiltrates on histology and absent or only partial repopulation.5 Other cases associated with combined mesotherapy have been described as patchy alopecia with progression and histology suggestive of anagen effluvium, followed by later resolution.6

There are 2 reported cases of “paradoxical” alopecia with patchy morphology and inflammatory appearance directly related to dutasteride mesotherapy.7 These authors associated these effects with the alcohol-based solution used in the preparation. This would coincide with our cases, all occurring in the context of alcohol-based solutions and intense pain during treatment. Dutasteride is a hydrophobic drug and has classically been prepared with alcohol and/or alcohol derivatives. Of note, alcohol is a potent cellular toxin, capable of producing apoptosis, overproduction of free radicals, or activation of autophagy. For all these reasons, dutasteride is currently preferably prepared in liposomal solutions for topical8 or infiltrative treatments.

Therefore, we describe 3 cases of an adverse effect that is currently poorly described and inadequately characterized in the literature. We believe that this effect is not directly produced by the active ingredient itself, but rather by the alcohol-based solution in which it is prepared. Therefore, given that less toxic injectable solutions are currently available, we do not recommend the use of dutasteride mesotherapy in alcohol-based solutions. Likewise, we consider it very important to recognize this possible adverse effect because of the striking nature of the condition and its self-limited course, which may help avoid associated anxiety and unnecessary treatments.

The authors report no conflicts of interest.