Why Does Hair Fall Out? A Look at the Hair Growth Cycle

Ever wondered why your hair sheds in the shower or why some people seem to lose more hair than others? The answer lies in your hair’s natural growth cycle – a repeating process that every strand goes through. Understanding how this cycle works (and what can interrupt it) is the key to understanding why hair falls out and how to encourage healthy regrowth.

The four stages of hair growth

Each strand of hair grows and sheds according to a specific rhythm made up of four phases:

Anagen (growth phase)

The longest phase, which can last between 2 and 8 years, this is when the hair is actively growing.

Catagen (transitional phase)

The hair stops growing, detaching from the blood supply.

Telogen (resting phase)

About 9% of total scalp hair is in this phase at any one time, which can last 2-3 months. While the old hair is resting, waiting to be shed, a new hair starts to develop at the base of the follicle, waiting to push the old hair out.

Exogen (shedding phase)

The new hair grows and pushes the old hair out. Follicle re-enters anagen.

What happens to the hair growth cycle during hair loss?

In somebody with healthy hair growth, the ratio of hair in anagen to telogen is 14:1 to 12:1, with approximately 100-150 hairs being shed each day. That might sound like a lot to lose every day, but most people have around 100,000 scalp hairs so losing 100 per day is equivalent to just 0.1%.

When hair loss occurs, the ratio of anagen to telogen may increase, causing more than the usual 100 or so hairs to be shed per day, leading to noticeable hair loss and reduction in hair density. Some common triggers which can disrupt the hair growth cycle include hormonal imbalances, stress, and vitamin deficiencies.

The most common form of hair loss in men is called androgenetic alopecia (aka male pattern baldness) and it is caused by the hormone dihydrotestosterone (DHT). DHT binds to the hair follicles, causing them to shrink and the anagen (growth) phase to shorten and the telogen (resting) phase to lengthen. Over time, new hairs grow back thinner, weaker, and shorter – eventually becoming too fine to break through the skin, which leads to visible baldness.

Other types of hair loss also involve disruptions to the hair growth cycle. Telogen effluvium is a type of hair loss which occurs when stressors like childbirth, surgery, or illness cause many hairs to abruptly move out of the growing phase into the resting phases earlier than they should, leading to excessive shedding.

What can you do about it?

If your hair loss is caused by male pattern baldness, it means your hair growth cycle has been disrupted by DHT, but it doesn’t mean there’s nothing you can do about it. Hair loss treatments can help set the hair growth cycle back on track so hair can reach its full growth potential again.

Finasteride is a licensed, clinically proven treatment for male pattern baldness. Finasteride works by blocking the enzyme 5α-reductase which converts testosterone into DHT. By reducing DHT levels, the hair growth cycle can go on as normal without disruption to the hair follicle.

Minoxidil Spray is the other licensed treatment, though how exactly it works for hair growth isn’t fully understood yet. It was originally used as a treatment for high blood pressure (and still is), but healthcare professionals noticed it had a strange side effect: hair growth. Now, it can be applied to the scalp to help with hair growth. It is thought to promote blood flow to the hair follicles, which is crucial for healthy growth as it supplies vital nutrients and oxygen. It may also lengthen the growth phase and shorten the resting phase, helping hair grow longer and stronger. Used together, Finasteride and Minoxidil have been shown to stop further hair loss in up to 94% of men.

If you think you are experiencing hair loss, you can take our free consultation for personalised recommendations on the best treatment plan for your stage of hair loss.

All of our blog articles are reviewed for medical accuracy by our Medical Director before publication.

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