Urticaria Induced by Laser Epilation: A Clinical and Histopathological Study with Extended Follow-Up in 36 Patients

In a retrospective study of 13,284 patients who underwent laser epilation with a 755 nm alexandrite laser, 36 patients developed a severe, itchy, persistent urticarial rash 6–72 hours post-treatment, primarily after the first session. The rash was most common on the legs and required oral corticosteroids for symptom control, resolving within 7–30 days. A history of allergies was reported in 33 of these patients, and skin biopsies indicated a possible delayed hypersensitivity reaction due to follicle disruption by the laser. The study suggests that an antigen from the disrupted hair follicle may trigger this reaction in predisposed individuals. To mitigate this side effect, the authors recommend an extended laser patch test followed by evaluation after 24–48 hours and preventive prednisone for patients who develop a rash in the test area.