Anything that disrupts the life cycle of hair can cause hair loss, or alopecia. Sometimes hair loss is temporary and reversible. If hair follicles are permanently damaged, however, the hair loss is permanent.
Types and Causes of Hair Loss
Male-pattern baldness, or androgenic alopecia, is hereditary: If your father was bald, chances are greater that you will be, too. Male-pattern baldness is also connected to hormones called androgens, specifically the androgen dihydrotestosterone (DHT). Some hair follicles are sensitive to DHT; it causes them to grow smaller (this is called follicular miniaturization) and affects their lifespan. Over the course of several growth cycles, the hairs from such follicles become thinner, finer, softer, and lighter in colour, until they resemble peach fuzz. Follicles that die stop producing hair altogether.
If you have male-pattern baldness, you may experience a receding hairline, thinning at your temples, and/or thinning at your crown (the top or highest part of the head). The exact pattern and rate of hair loss varies. You may begin losing hair at any age after puberty, and the hair loss may stop and start over the course of your life. You may or may not become completely bald, and the process may or may not be partially reversible.
Alopecia areata (spot baldness) is also hereditary and affects 1–2% of the population. It is caused by white blood cells attacking and destroying the hair follicles (why they do this is unknown). As the name suggests, alopecia areata involves round spots of hair loss; 80% of people with this condition have only 1 bald spot. A very small percentage of people with alopecia areata will eventually experience thinning hair everywhere (diffuse alopecia).
One clue distinguishing alopecia areata is the presence of strong pointed hairs on the perimeter of the bald patch that are easy to pull out. Also, the area of bald scalp may appear peach-colored.
Alopecia areata can occur at any age, but the majority are between 15 and 29. It might be temporary, particularly if you are older. In 90% of cases, hair grows back on its own; if you are over 40 and have only a small bald spot, it is likely your hair will grow back.
Scarring alopecia occurs when hair follicles are damaged or destroyed. It can be caused by infections, disease, or illness. Hair loss is permanent.
Telogen effluvium (TE) is the tremendous loss of hairs—more than 400 a day—during the resting phase of the hair's life cycle. Telogen effluvium may be temporary or chronic, and it can be triggered by any number of emotionally or physiologically stressful events, such as chronic illness or surgery.
More Causes of Hair LossChemotherapy doesn’t just kill cancer cells, it kills any cells that divide rapidly, like cells in the hair follicle. You can expect to lose 90% of your hair during treatment, but it will start to grow back 6–8 weeks later (it may look and feel different). Within a year, you will have your regular hair back. Radiation to treat cancer can also cause hair loss in the areas exposed to it.
Trichotillomania is the compulsion to pull out one’s hair. This is more common in women and children than men.
Hair loss can also be caused by:
- Chronic medical conditions, such as diabetes and lupus—About 50% of people with lupus experience hair loss; it may or may not be permanent.
- Medications—Hair loss can be a side effect of many drugs and medications.
- Diet—nutritional deficiencies, eating disorders and harsh diets result in thinning hair.
- Stress—If you have a genetic predisposition to hair loss, stress can cause permanent hair loss to occur earlier and rapidly.