Pulsed-dye laser (PDL), as an effective and frequently-used treatment modality for infantile hemangiomas (IH), could render patients at risk of developing long-term alopecia. Data on alopecia caused by PDL treatment remain scant and the contributing factors are not clear. Our objective was to identify the risk factors associated with long-term alopecia resulting from PDL treatment for scalp IH. We conducted a retrospective study incorporating patients with IH diagnosis and PDL intervention via thoroughly reviewing the clinical database of the dermatology department. Scalp IH patients were further screened and their medical records were collected. Long-term alopecia was defined as no signs of terminal hair regrowth for at least 2 years in this study. Of the 1293 IH patients, 47 (14 boys and 33 girls) with a mean age of 4.5 months (standard deviation, 3.2) were diagnosed as scalp IH and had subsequently undergone PDL treatments. Hair growth in the treatment area of 18 patients (38.3%) nearly returned to normal, 22 patients (46.8%) had varying degrees of hair loss, and seven patients (14.9%) had no hair regrowth (long-term alopecia). Compared with the older patients receiving treatment, IH patients younger than 3 months who started PDL treatment had a higher risk of developing long-term alopecia (odds ratio, 30.833; 95% confidence interval, 4.079-232.025; p = 0.01). The total number of PDL sessions, post-treatment blisters, and location of IH were not shown to be significantly associated with the development of long-term alopecia. Collectively, our study provides an important insight into curating treatments for IH in infants younger than 3 months. PDL treatments for scalp IH may perhaps be avoided or delayed to prevent the development of treatment-associated long-term alopecia.