LAUSR

Dear Editor, Acne vulgaris is a common disease of teenagers that may continue until adulthood. Isotretinoin (ISO) (13cis retinoic acid) is the most renewed treatment for moderatetosevere acne. ISO should be introduced precociously for mildtomoderate acne not responding to conventional therapy, if there is no formal contraindication.1,2 ISO has dosedependent side effects, which are secondary to retinoic acid receptors expression in the tissues. These side effects are reversible with drug discontinuation. ISOinduced dryness of the skin and mucocutaneous membranes is the common known side effect.3 Data on ISOrelated hair disorders are limited in the literature, even in the era of COVID19 and related vaccines. Herein, we have reported acne patients on ISO in two hospitals in Turkey presented with hair disorders between December 2020 and March 2022 (Figure 1 and Table 1). The patients were otherwise healthy 21 females, with a mean age of 20 years, who were on ISO for acne vulgaris (7 mild, 8 moderate, and 4 severe degrees, according to The Global Acne Scarring Grading System 4) presented with hirsutism (6) or telogen effluvium (TE) (15) during the course of ISO. None of hirsute patients had history of menses irregularities, polycystic ovary syndrome (PCOS), or on antiandrogenic therapy. The dose range of ISO was 0.25– 0.5 mg/kg/day. The average cumulative dose was 2543 mg. The mean duration of ISO course at time of presentation was 11.8 weeks. The mean time of onset of hair disorders was 6.9 weeks. Five patients had history of paucisymptomatic, PCRconfirmed COVID19 prior to presentation. The average duration of COVID19 symptoms was 2,2 weeks. For those with COVID19 history, ISO commenced after 1 month of recovery in 1 case, and after 6 months in five. Five cases had prior history of COVID19 vaccination, one of them in the second month of ISO (case 16). None of the patients had discontinued ISO. The mean time of recovery for TE was 5.2 weeks. Follow up is being for hirsute patients. Hair loss in the form of TE is a reported side effect of ISO that can lead to treatment discontinuation. Retinoids possibly arrest the onset of the anagen phase of the hair cycle and impair the anchoring of hair during the telogen phase, ultimately increasing hair shedding.5 In a study by Hull et al. on 124 adolescents and adults using ISO for acne, it was reported that hair loss increased from 7% in the fourth month of treatment to 14% at the end of treatment.6 İslamoğlu et al. noted that ISO in low doses and short courses of therapy did not affect hair parameters or lead to TE.7 Lytvynet al. reported that patients on <0.5 mg/kg/d of ISO experienced hair loss at a frequency of 3.2% versus those on ≥0.5 mg/kg/d, who experienced hair loss at a frequency of 5.7%. The authors suggested lowdose ISO as an alternative approach to drug discontinuation.3 Aksac et al. noted that addition of 10 mg/day biotin to ISO has increased the rate of anagen hair and reduced the rate of telogen hair, eventually could help in lessening the risk of ISOinduced hair loss.8 COVID19associated TE (CATE), a form of hair loss developed several weeks after recovery from COVID19, is estimated to occur in up to 60% of SARSCoV2 infected patients. Therefore, exclusion of COVID19 history is important in any patient presented with hair loss and has been diagnosed with TE.9 CATE is expected to resolve spontaneously within 1– 6 months of onset. However, minoxidil,