Alopecia is, simply put, hair loss. If you have alopecia, you might see extra hair on pillows or in shower drains, or you might notice bald patches on your scalp. Over time hair loss can grow back or fall out permanently, depending on the cause. Alopecia is not curable, but it's treatable and not life-threatening.
Here are some of the possible causes of alopecia.
Genes and Hormones
Androgenic alopecia, also known as male pattern baldness or female pattern baldness, is the most common type of alopecia. In men, it causes balding and a receding hairline, while women may experience general hair thinning or a widening of their part. Androgenic alopecia can be genetic, and it’s also hormonal.
Dihydrotestosterone (DHT) is a hormone derived from testosterone, the male sex hormone. DHT binds to testosterone in hair follicles and weakens them. Women also have testosterone. When testosterone and estrogen, the female sex hormone, are unbalanced in women, DHT can trigger androgenic alopecia. This can happen before menopause or with other hormonal conditions, Beverly Hills-based dermatologist Tsippora Shainhouse, MD, FAAD, tells WebMD Connect to Care.
“Some women have a condition called polycystic ovarian syndrome (PCOS), in which they make so much estrogen, that some gets converted to testosterone, which can contribute to thinning and loss of hair,” Shainhouse says.
Alopecia areata is a condition where the immune system attacks hair follicles. It could also be genetic in some cases, says the American Academy of Dermatology (AAD).
Telogen effluvium is a type of alopecia where hair sheds in excess. It can happen suddenly, or hair can thin over time. Causes of telogen effluvium include:
- Physical trauma
- Restrictive dieting
- Life changes
Women are more likely to report telogen effluvium. A 2019 study in the journal Clinical, Cosmetic, and Investigational Dermatology found men might not notice telogen effluvium because of shorter haircuts or lack of attention to hair.
“For some women, this hair loss unmasks an underlying female-pattern hair loss, and the hair may never look as thick as it once did. If you are otherwise healthy, then treatment is mostly a watch-and-wait game,” Shainhouse says.
Alopecia areata can also be triggered by:
- Hay fever
Nutritional deficiencies, including low iron or vitamin D, could cause alopecia, says Shainhouse. But when it comes to vitamin D and hair loss, more research is needed, according to the AAD.
“See your primary care physician to treat these, in order to give your hair the best chance of growing back,” Shainhouse says. “Develop a healthy eating schedule that includes food-derived vitamins and nutrients, and ... enough protein.”
The thyroid is a neck gland that controls metabolism-related hormones. Both low and overactive thyroid can trigger alopecia. Ask your doctor about a thyroid test if your hair loss is accompanied by:
- Unexplained weight changes
- High or low energy
- Menstruation changes