The Hair Growth Cycle & Laser/IPL Treatments. When is the ‘best’ time to treat?

Hair grows in a well-known cycle – anagen, catagen and telogen.

The ‘active’ growing phase is anagen – during this phase the hair follicle will begin to grow from a single stem cell. The duration of this phase depends on the body location and can range from a few weeks to several years!

However, these phases ‘overlap’ in any particular skin area. In other words, when we look at the skin, we see hairs in all phases, at all times! It is quite difficult to see which hair is in which phase. This poses problems for laser/IPL hair removal operators.

The following image shows how these phases may be arranged for hair on the legs, upper lip, eyebrows and arms. As you can see, there really is a wide variation in all phases, except catagen.

In most hairs, the catagen phase lasts for only two to three weeks. During this stage the hair shaft detaches from the root and ‘rises’ up through the follicle awards the surface. This is often referred to as the ‘transition’ phase and the hair is known as a ‘club’ hair at this time.

The telogen phase is the ‘resting’ stage where all growth activity has stopped. Hairs usually shed during this phase – typically up to around 100 per day.

Once the follicle goes back into the anagen phase, the newly growing hair will ‘push’ out the club hair and replace it.

Hair Growth Cycle – Legs

Let’s look at the growth cycle for leg hair.

Generally, around 20% of leg hair is in the anagen phase at any one time. This leaves the remaining 80% in catagen and telogen phases – mostly in telogen.

The ‘over-lapping’ growth phases of leg hair. Click on the above image to download a larger image.

When looking into the ‘over-lapping’ nature of the growth cycle, it becomes clear that the ‘best’ time to carry out any light-based treatment – laser or IPL – should be chosen to coincide with the anagen phase of the cycle.

In other words, treatments should be repeated according to the anagen phase of the cycle. For legs, this is every 16 weeks! By doing this you ensure that you have the maximum number of active, anagen, follicles to target. Carrying out treatments before this time is pointless and wasteful. It will result in too many treatments with little gain, and unhappy patients!

How often do you go for a haircut? Most people leave around four to eight weeks between haircuts. Why? Because of the time it takes to ‘grow back’! There’s no point going any sooner because there won’t be enough growth. Well, it’s the same for laser/IPL treatments.

So, what about other body areas?

According to the anagen phases of hair across the body, here are our recommended treatment times:

AreaTime between sessions
Eyebrows6 – 8 weeks
Arms13 weeks
Upper lip16 weeks
Under-arms16 weeks
Bikini6 months

This is quite surprising, especially as we’re told to leave “six weeks’ between treatments. But this is wrong! The timings are set by the hair growth phase – not some arbitrary time!!

We will discuss this topic more fully in our upcoming eBook, which will be available soon – click here for more info.

Hope this helps,


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s