Background: Although hair reduction by long-pulsed red and infrared lasers and light sources is generally quite effective, paradoxical hair growth has rarely been observed following treatment.
Objective: To report a case of thick hair growth following 810 nm diode laser treatment and its subsequent treatment. METHODS. A 24-year-old man who had previously had laser hair reduction on his posterior neck was treated to a test area on his upper back.
Results: Thick terminal hair developed in the treated area subsequent to laser treatment. Further treatment of this area removed the terminal hair but resulted in terminal hair growth in an annular distribution surrounding the treatment site.
Conclusions: Diode laser treatment rarely stimulates terminal hair growth. This phenomenon should be studied to better understand hair growth cycles and to help develop more effective treatments for hair loss and hair growth.