We often hear about ‘paradoxical hypertrichosis’ – unexpected hair growth – after laser treatments.
No one seems to know why this happens. There is very little research on this topic too.
So, what is going on?
Well, I don’t think it is actually paradoxical hair growth at all. I think that, in many cases, we are just seeing follicles growing back, after being under-treated by lasers or IPLs.
If too low a fluence is applied to hair follicles, they will most likely survive. It appears that such follicles soon go into catagen and then telogen – no matter where they were in the anagen phase.
Those follicles will then go into a new anagen phase, in due course. At the same time, the follicles which were due to go into anagen, will also do so.
The result is a greater growth of hair follicles than might be usually expected. There is some evidence that repeated, sub-threshold treatments might even force the hair growth to ‘synchronise’. Many follicles begin to grow around the same time, whereas, usually it is more random.
This can also occur even if the proper fluences are applied. Not all the follicles will be destroyed, even when high fluences are used. This is simply because some of those follicles will be too deep to kill.
Those ‘stunned’ follicles will regrow, earlier than normal, and usually finer and light in colour.
As a consequence, it will appear that more hair than normal is growing – even after ‘successful’ treatments.
Buttocks!!!
Hope this helps, a bit!
Mike.
Mike Murphy's Blog 