Paradoxical Laser Hair Stimulation

Re-posted as a sticky from the ‘Be careful’ thread.

[size:14pt]Paradoxical Laser Hair Stimulation[/size]

The use of lasers to remove hair has become very popular in recent years. However, there are sometimes strange phenomena that occur when lasers are used to remove unwanted hair. On rare occasions, instead of removing hair, laser treatments can actually promote hair growth. This phenomena, known as hypertrichosisis, is paradoxical effect of laser epilation. The new hair growth is actually created in part by the effect of the laser although this effect and how it occurs is not yet completely understood. Scientists are now searching for a better understanding of the mechanism behind this paradoxical effect of laser induced hypertrichosis so as to prevent it in future cases.

In order to better understand this phenomenon, scientists set up an experiment using an alexandrite laser to remove the unwanted hair of 489 patients. The patients had all been customers at a single laser hair removal clinic at the University of British Columbia Dermatology Division in Canada, and were treated by trained nurses and supervised by board certified dermatologists. Out of these 489 patients, only 3 cases of laser induced hypertrichosis were identified, but these cases were enough to offer further information on this rare phenomenon.

The three patients who had experienced an increased amount of hair growth instead of a decrease became the focus of further study. Paradoxical hypertrichosis had been seen before in other cases, but it had not been so carefully watched. Scientists first identified the hypertrichosis in each of the three patients by noting an increase in hair density, hair color or hair coarseness after laser application. Once this definition was established, they began to examine each individual case more closely.

One of the patients who experienced this increase was a 39 year old Mediterranean woman with black hair. At first, when the laser was applied to an area with unwanted hair, the hair growth decreased just as it was supposed to. However, the continued applications of the laser resulted in increasingly stubborn hair that would simply not respond to the treatment. Eventually, the woman reported a gradual increase in hair density around that area rather than a decrease.

A second patient who experienced an increased quality of hair growth was a 30 year old white man with black hair on both his arms and his back. The man had wished to have some of this hair removed from his back, but the treatment was not successful. During the first three sessions, he experienced a positive result where the unwanted hair began to slowly disappear. However, further treatments began to require higher and higher intensities of laser light in order to be successful. After six visits to the clinic, the man began to notice an increase in hair growth rather than a decrease. This was only noticed at the specific locations where he had been receiving the treatments. Even with a further increase of laser intensity, there was no success and the man abandoned the treatment entirely.

The third patient who experienced laser induced hypertrichosis was a 21 year old Chinese man with black hair. Besides the common factor of black hair, which existed in all three of these patients, there was a similar skin type amongst them known as Fitzpatrick “Skin Type IV”. Skin type IV indicates a darker level of skin that rarely burns with sunlight exposure (as opposed to skin type I, which is very white skin that easily burns when exposed to sunlight). Out of six different skin types in the Fitzpatrick skin type classification; this skin type IV was the only type of skin that was known to have been adversely affected by laser hair removal treatment in any of the 489 patients. Hair color and skin type may have obviously contributed to the hypertrichosis because, just like the other two patients, this third Chinese man began to notice an increased growth after 11 days of the laser epilation.

The results of the testing were compiled and analyzed so that the most obvious cause of the hypertrichosis was determined to be a result of the laser epilation itself. This was evident from the fact that the increased hair growth only occurred in the areas that were treated by the laser but, more specifically, scientists have determined that the problem may be a result of the wrong intensity of laser light rather than just the laser light itself. These ideas are being tested further and it is the hope of scientists that a solution to this rare adverse hair growth occurrence can be corrected in type IV patients.

Paradoxical hypertrichosis after laser epilation references

Alajlan A, Shapiro J, Rivers JK, MacDonald N, Wiggin J, Lui H. Paradoxical hypertrichosis after laser epilation. J Am Acad Dermatol. 2005 Jul;53(1):85-8. PMID: 15965427

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It doesn’t appear to occur as often, as it would seem to us electrologists. Personally I have noticed its’ occurance in several fair skinned individuals. Perhaps operator skill is a factor too.

I’m wondering why they also used the alexandrite on someone whose a skin type IV, which seems to run counter to the advice about using a YAG for that skin type

One of the conclusions of this study about effect of IPL (in the face of 52 women), funded partially by the University of Barcelona:

Figure 35. The appearance of fine terminal hair in untreated areas adjacent to treated area was observed in five patients carrying the syndrome polycystic ovarian disease. The diagram explains how the light scattered from the treated area would have a subtherapeutic effect, that would trigger the follicles of the adjacent untreated area, causing terminal hair.

When they report three out of one hundred had laser hair stimulation, that makes me curious. That is why a national / internatonal data bank would be helpful. I seem to see more and more clients with this frustrating side effect and it personally deflates me to hear their stories. With that said, I am a fan of laser reduction for certain body areas. It does a fabulous job to whack out a lot of hair. If laser reduction was not an option, I would be booked until December 2012. That would be overwhelming indeed, something I do not want.

Great post I must say. It really worries me that all of this PLHS is not studied enough and that this problem seems to be overlooked or not even accounted or known in most laser clinics throughout the world. Mostly in my country.

It also worries me that this tends to happen in darker skins more often…

Also the patient number two intrigues me. The story of him having three treatments and all seemed to go well and then it got worse. It really bothers me and worries me about possible future treatments I could make.

A SUGGESTION: As I’ve seen the “post success stories”, I think it would be great to have a place to gather STORIES AND INFORMATION of cases of paradoxical laser hair stimulation.

-areas treated
-type of skin
-coarseness of the hair

I think it would be very good for the forum as it would make more clear what/who can and shouldn’t be treated with laser.

I know it may seem a bad idea for some because it can make people worried, etc… but I think telling about these things is the way to go. Also, I only make this suggestion to laser/ipl treatments because as far as I know they’re the only ones that can trigger MORE hair growth, I’m not talking about scars or treatments that simply don’t work. Some people search for these treatments because their hair makes them really uncomfortable/depressed, to make their problem worse is as bad as telling someone who suffers from an eating disorder that they’re fat.

Just a suggestion, thank you all. I’m glad I’ve found you.

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That is a wonderful suggestion. Thanks! I have no idea if this is a rare occurrence or not for a woman’s face and neck and male upper backs, upper arms and shoulders.

I will run your idea by Andrea and James and see what we can do.

What can one do to reverse the effect of paradoxical laser hair stimulation?

It cannot be ‘reversed’. You must either live with this new hair or have it permanently removed with electrolysis.

How about if you do laser and apply Vaniqa? Would that help?

Stopit&tidyup Do you know any good Electrologists in London?

One of my clients suffers from induced hair growth caused by vaniqua.

Anyway: vaniqa reduces hair growth only during the time it is applied regularly. “Reduces” does often just mean that the hair is growing slower.

Beate r. Thanks for the information! My dermatologist told me that it can’t make matters worse. I was a bit suspicious. Thanks for setting that straight.


My electrologist in London was Sharon at Parkside Beauty Centre.

Wowee! This is the first time I heard this! Is this your client’s personal conclusion? This should be reported. I believe there is a form on the FDA website to do this? Or, maybe the prescribing physician should be told? I am really curious about this one. I can’t find anything on the internet so far about this, Beate. It is not a life threatening side effect, but if you think this should be reported, here is some information:

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

I don’t think PLHS is that rare, as an electrologist having returned to Scotland just over a year ago, and now working mainly on Celtic skin types I have already encounter this kind of promoted hair growth. I have had 5 clients so far with this problem. Laser/ipl not sure which, seems to cause this problem on the neck and sideburn area, typical hair growth that I have seen from PLHS is fine long and dark. Will be interesting to see if the scientists can come up with any answers?

I see this enough times where I would not label it as rare. I also see fabulous results with LASER, which makes my job easier. Clients need to be INFORMED of the possibility that this may or may not happen and then be willing to invest more time, money and effort in electrolysis to clean up the extra hair.

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Many clients have had successful laser treatments. Though many are also spending too many years having treatments without making progress. I agree Dee the public have to be better informed, thank goodness for websites like this.

Can more laser get rid of paradoxical laser hair stimulation or is the new hair untreatable?

Laser places will tell you ‘yes’.

I have not come across anyone who has experienced this and then found further laser improves the situation. And I know a number of people who carried on for a year or more after already going through a course of treatments which lead to laser induced growth.

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