4 reasons why your hair might be falling out
Dr Cathy Stephenson is a GP and forensic medical examiner.
We all go through stages where we suddenly seem to lose far more hair than usual – this can be a normal part of the hair "cycle".
However, it can signify something else going on in your body. To figure out whether or not you should be concerned, you first need to understand the normal life cycle of your hair.
Each hair follicle on our scalp will produce a number of hairs in a lifetime. These hairs go through three distinct phases:
- Anagen or growth phase – around 85 per cent of our hairs are in the growth phase at any one time; during this phase the hair can grow around 1cm per month. Anagen phase can last anywhere from 2-8 years, and how long it lasts will determine how long your hair could grow if left uncut.
- Catagen or transition phase – once the hair growth has finished, the hair goes into a stage of transition, when the hair follicle shrinks down. This lasts 2-3 weeks.
- Telogen or dormant phase – this can last 2-3 months, and during this stage the hair just rests, not growing at all.
At the end of the telogen phase, the follicle starts to enter a new cycle of hair growth, pushing out the old hair (known as "shedding"). Usually, humans shed around 50-100 hairs each day, as distinct from animals who shed in a much more seasonal way.
Any event or illness that disturbs the normal cycle of hair growth can result in unexpected hair loss. The degree and pattern of loss can help you decide whether or not it is normal, or whether you should be discussing it with your doctor.
1. Male or female pattern baldness
This is a normal part of ageing, but will happen to different degrees in people, depending on their ethnicity and genetic predisposition. When we get older, less hairs enter the anagen or growth phase, and they become thinner and more fragile, falling out more easily.
In women this tends to be in a diffuse pattern, with gradual thinning and loss all over the scalp; whereas men tend to get the more typical loss around the temples, or top of the head.
2. Alopecia areata
The word alopecia means hair loss, and it can be entirely normal as in the alopecia associated with ageing above. However, alopecia areata is not a normal part of ageing, and is worth talking to your doctor about in case it is part of an underlying medical problem.
This type of hair loss classically happens in discrete patches, where all the hairs in one area come out at once. Sometimes this will only affect a tiny patch of your scalp, eyebrow or beard area, but for other people it can be really extensive, covering more than 50 per cent of their head.
Understandably this can lead to significant distress and worry. It can be associated with autoimmune conditions such as lupus, thyroid disease, vitiligo and diabetes. It is also thought to be associated with stress.
3. Telogen effluvium
This type of hair loss occurs when more hairs than usual are pushed into the telogen (dormant) phase, causing a sudden shedding of hair from all over the scalp. It is usually precipitated by a physiological or hormonal trigger, including childbirth, iron or zinc deficiency, sudden weight loss, major surgery, severe infection, or even a change in medication such as an antidepressant or the contraceptive pill. The good news is it nearly always regrows after 3-6 months.
4. Anagen effluvium
This distressing condition is when hair growth stops suddenly in the anagen phase, usually resulting in complete hair loss. It is nearly always the result of chemotherapy. For most people, hair will regrow within a few months of stopping treatment.
There are other rare conditions that can cause hair loss too, so if you think your hair loss is unusual in any way, or is causing you concern, please ask your doctor for more information.
Written by Dr Cathy Stephenson. Republished with permission of Stuff.co.nz.