I apologize if threads on this topic have been posted already. I don't frequent the medical sciences forum. My question is whether there are any rigorous scientific results published in peer-reviewed journals on the efficacy of what seems have been dubbed "low level laser therapy" (LLLT) as a treatment for male pattern baldness (i.e. laser light that stimulates follicles/cells to regrow hair). It seems to be a bit of a cottage industry, with a bunch of clinics springing up and business models developing. I went to a clinic for a free consultation. Of course, I was an "excellent" candidate. What they are offering is very expensive, and the overwhelming negative reviews of people on this forum who have actually tried out or are in the midst of trying out the very same clinic: http://www.baldtruthtalk.com/showthread.php?t=1540 have me convinced that it is a scam, at least in the sense that the same products (e.g. portable "laser combs") are being offered through the clinic at significantly higher prices than similar products that manufacturers will just sell you (by a factor 2-3!) Yet, if you go to the company that makes the "HairMax" laser comb, claimed to the only one in the industry to be FDA approved for marketing as a hair loss treatment product, and you look a little more deeply in to said "FDA" approval, you just find that all the FDA said was that the device was similar enough to other "predicate" devices sold since before some date in the 1970's for similar *enough* applications that the company in question could skip a bunch of red tape and get approval to market it now. In short: approved for marketing, ruled as non-harmful. But no ruling one way or another on its effectiveness. http://hairmax.com/Home.aspx http://www.accessdata.fda.gov/cdrh_docs/pdf6/K060305.pdf The website is quite misleading in that regard. In fact, only one of their models is approved in this manner, so that if you click on the link for the other model, it says "NOT FDA APPROVED!" Not for sale in the USA! In fact, the website of their Canadian subsidiary has a much wider range of models, probably for this very reason! Quite hilarious. http://www.freedomhair.com/hairmax/ As for the efficacy, the only thing I came across was this YouTube video from a Dr. Alan Felder calling it "junk science", and demonstrating that a laser beam (presumably of the same wavelength range and power output as those being sold for LLLT, although he makes no effort to quantify anything) cannot even penetrate a piece of tissue paper, therefore there is no way it could reach the hair follicle to stimulate it. I take issue with some of his statements, which demonstrate that he does not have a very good knowledge of physics. For instance, he says that the "dot becomes bigger", losing its "laser character" and turning into "ordinary red light," becoming effectively the same as red LED light shone into the skin. Well, as many on this forum will know, his first point just means that the light gets scattered. Whether or not it "loses it's laser" character is question that must be posed more specifically. Obviously the collimation of the beam is lost, but the monochromaticity and the coherence are preserved. He makes no reference to these concepts, and erroneously states that the light is exactly the same as red LED light which probably has a much wider bandwidth. That having been said, my nitpicks of his physics are probably irrelevant, particularly in the absence of any evidence that the aspects of "laser character" that are retained actually do anything. Who is to say whether that wavelength is more effective in stimulating cells than other ones? And he may have a point about scattering (although he did not use the term). When we say a laser diode is much more "powerful" than an LED, I'm sure we're talking about intensity (W/cm2). If the laser light is diffused and scattered before significant power can reach the depth required, then what good is that? Again, I just don't *know.* He makes no effort to present anything quantitative, and he does hair transplants, which means he has as much of a vested interest in all of this as anybody else. The only info I could find about the depth of hair follicles is that they are located in the dermis, below the epidermis, and that these two layers vary in thickness from 0.05 mm - 1.5 mm (epi) and 0.3 mm - 3 mm (dermis) depending on where on the body you look.