I often see laser/IPL users making comments like “the hair grows back after a treatment…”, or something similar.
When we treat hair with light energy, we cannot expect to kill all of those in the anagen phase (laser/IPL light can kill only the anagen follicles). In reality, most operators might kill between 50 to 80% of the active anagen follicles. If treated correctly, those follicles will not regenerate (if ALL their germ cells are ‘cooked’ properly).
After each treatment the surviving anagen follicles will continue to grow, maybe after a ‘quiet’ period. All the telogen follicles will eventually return to anagen. All of these processes will occur in the days, weeks and months after any treatment.
So, after every treatment, some follicles will continue to grow. When laser/IPL operators say “the hairs grow back”, they are wrong! What they are seeing are the surviving follicles continuing to grow, and some of the telogen follicles becoming anagen.
They should not be seeing any hairs “regrowing”, if those follicles are dead!!
This should be explained to clients/patients so that they understand what is going on after each treatment, and what they should expect to see.
My recent calculations show that the ‘best’ results happen after the first treatment session. If done well, somewhere between 26 and 46% of the anagen follicles may be killed in the first treatment. But these percentages decrease with every subsequent treatment – simply because there are fewer follicles left to target!
With hair removal, it’s always a case of ‘diminishing returns’.
So, be careful with your choice of language – you might give the wrong impression!!
Hope this helps,