Understanding how hair develops and grows will give you a better idea of how and why hair-loss occurs.

How does hair grow?

Each hair develops from a single follicle, a small pocket in the skin, and you have millions of hair follicles on your head. Each hair goes through three phases of growth during its life cycle.

First is the active growth phase, called the “anagen” phase. This lasts for a few years. During this time, your hair follicle produces a hair bulb at the base of the follicle, with a strand slowly protruding from the hair follicle and out above the surface of your skin. Your hair grows, on average, by about 1 centimeter per month.

Most of the hair on your head – about 90%! – is in this active growth phase.

Follicle Diagram

After a few years (usually 2 to 7) the hair follicle enters the “catagen” phase. This lasts for 2 to 3 weeks and is considered a transitional period. This is the tail end of the hair production process, when the follicle begins to retract from the scalp and the hair stops growing.

Last is the “telogen” phase, when the hair is no longer growing but remains attached to its follicle for a few weeks to a few months. This is when the hair falls out.

After the telogen phase, the anagen phase begins again, completing this long cycle.

Why does hair loss occur?

Normally, we lose 50 to 100 strands of hair per day as part of the natural growth cycle.

When hair loss and patchy hair occurs, there are usually two reasons. The anagen phase (remember, this is the growth phase) is getting shorter. Meanwhile, the telogen phase (or resting period) is getting longer. In a process called “follicular miniaturization,” the hair follicle is also changing, shrinking and generating a thinner and shorter hair shaft. Ultimately, this means fewer, thinner hairs on your head for a shorter amount of time.

If you’re not already familiar with the hormone DHT, read all about it here. It’s crucial in understanding hair loss, because most people who experience hair loss as they get older are just genetically susceptible to the effects of DHT. Your hair follicle cells have been over-exposed to DHT and simply don’t like its effects anymore.

Blocking DHT is one powerful way to slow and stop hair-loss.


Want to find out if you are predisposed to high levels of DHT? Take our quiz below!