The amount of home use devices have increased exponentially the last couple of years, but how effective are they really?
There is no manufacturer or seller who doesn’t have a list as long as my arm of happy clients according to their seller reviews.
Just why is it that a little device costing less than €400 seems to be able to do permanent hair removal just as well as a €40000 machine? The short answer is that it doesn’t. The secret is that it causes shedding and it is a common misperception that shedding is equal to permanent hair removal.
Protein denaturation starts at about 41 °C. This is not that much higher than normal body temperature of 37 °C and that is also why it is possible to have hair loss because of high or extended fever (telogen effluvium).
Sufficient protein denaturation in the follicle causes shedding. Although not every device will give enough energy to cause shedding, it has become quite common for these devices to do so. The hairs that shed will return during the next growth cycle. The trick here is that if a user does regular treatments (s)he will cause the hair to shed earlier in the growth cycle and therefore the visible hairs will become less and finer.
The damage caused to the follicle by temperatures under 48 °C is reversible and of temporary effect. To cause permanent hair removal / reduction you need to create irreversible damage and you will have to heat the dermal papilla up to over 65 °C for a minimum length of time. The thermal damage time (TDT) for hair range between 200 ms and 400 ms.
The energy needed to cause this temperature rise at the depth of the dermal papilla can cause permanent blindness. This is why lasers suitable for permanent hair removal are always class 4 lasers. However, it is possible to have shedding with class 1 or class 2 lasers.
Coming back to the question: How effective are home-use lasers and IPL’s for hair removal? It seems that the technology has matured to such extent that temporary hair removal can be done quite effectively with a home device. Permanent hair removal / reduction is still an exception to the norm for these devices and will remain so because of the safety restrictions on class 4 lasers.