Laser Hair Removal May Stimulate Growth

(Dermatologic Surgery, June 2003)
Anaheim, Calif.

Some individuals having a laser procedure for hair removal are getting the opposite of what they desire: new terminal hair growth adjacent to treated areas. “This is real, and it’s out there,” Dr. Ranella J. Hirsch said at the annual meeting of the American Society for Laser Medicine and Surgery. “There seems to be a  predominance in the chin and sideburn area.”  Among those who have seen and treated this paradoxical effect, there has been a sense that the blame lies with lasers with shorter wave lengths used at fluences that are too low –the kind of undertreatment mistake more likely to be made by inexperienced physicians and boutique cosmeticians. “That appears to be only partially true, however,” said Dr. Hirsch of the Wellman Laboratories of Photomedicine at Massachusetts General Hospital, Boston. Dr. Hirsch   reported on 12 of these cases –and said she has heard of more than 100- and they are associated with many types of lasers and fluences used. “We know of physician-treated cases and there was nothing done wrong.” She said in an interview. The types of lasers used  in the cases she has collected run the gamut from the 694-nm long pulsed ruby laser and the 800-nm diode laser to the 1,064-nm neodymium: YAG laser. There is a published report of hypertrichosis associated with intense pulsed light treatment. Most of the cases occur in treated women with olive or darker complexions, from Fitzpatrick skin type III to V. “But even that is just a tendency, not a rule”, Dr. Hirsch said in the interview. She knows of the case of a blonde, blue-eyed woman-“a true Fitzpatrick type II – who suddenly grew a patch of chest hair following a treatment for hairs on the neck. “Removing the new hair growth requires diligence because a patient with a darker skin type is the kind of patient in whom it is easy to damage pigment,” Dr. Hirsch said. When she treats a patient with this type of hypertrichosis, she uses a long wavelength, short pulses, and a high fluence. Because of the care that must be taken some individuals require 10-15 treatments for adequate removal. Is this hypertrichosis truly initiated by treatment? “Although it is considered a myth that such things as shaving can transform vellus hair into thick terminal hair, it is possible to theorize that heat injury could stimulate follicles to enter an anagen phase through the signaling protein known as Sonic hedge-hog”, Dr. Hirsch said. “We don’t know, but it certainly makes sense,” she added.

Editors’ note: We have received calls from members of this phenomenon occurring. If you have patients who have reported a similar problem, have this information available for them. It is from a credible source and not just the electrologist who may be viewed as having a biased opinion.

 Electrology World 2003-Vol.22 , Issue 3