“Seeing the Light” – or, how to remove hair properly using light energy


Permanent hair removal IS POSSIBLE – but only if you know how!

Open PDF version for an article I wrote.

Hair removal, by light, is routine these days’ across the world. A number of devices are used to achieve this – IPLs, diode lasers, alexandrite lasers and others. They all operate by generating heat within the hair shaft leading to protein denaturation.

Some years ago then FDA decided that “permanent” hair removal could not be used by manufacturers and operators. It had to be called “hair reduction” – whatever that means!

They based this change on the fact that many operators were not achieving permanent hair removal. IPLs, in particular, got a lot of bad press.

The reason many people were not achieving permanent hair removal is simply because they were not using their equipment properly! The target cells in the hair removal process are the germ cells located around the hair bulb. Light energy absorbed by the melanin in the hair shaft creates heat energy which conducts to the germ cells (only in the anagen phase).

If a sufficiently high temperature is maintained for a sufficiently long period of time then the cell proteins will denature irreversibly. This means that the hair follicle will likely die and not regrow. If either the temperature is too low or the pulse too short, then finer hairs can grow back. These are more difficult to remove!

The problem is how to know the correct temperature and time to ensure a good result. This is the tricky bit….

The temperature achieved in the hair shaft depends on the hair colour and diameter, its depth and the incident energy level (and pulse duration). How long it stays at any particular temperature depends strongly on the hair diameter but also on the pulse duration. Longer pulses keep temperatures higher for longer (obviously!!).

In fact, calculations clearly indicate that longer pulses will generally result in better outcomes, regardless of the size of the hair (given a sufficient energy).

So, if you find your patients are returning after treatment with finer hairs then consider using the same energy as previously but with longer pulse durations. That should increase the probability of ensuring protein denaturation within the germ cells, which hopefully will lead to permanent hair removal.



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