Any kind of physical trauma—surgery, a car accident, or a severe illness, even the flu—can cause temporary hair loss. This can trigger a type of hair loss called telogen effluvium. Hair has a programmed life cycle: a growth phase, rest phase and shedding phase. eg: Pregnancy
Lack of protein
If you don’t get enough protein in your diet, your body may ration protein by shutting down hair growth. This can happen about two to three months after a drop in protein intake
Female-pattern hair loss, called androgenic or androgenetic alopecia, is basically the female version of male pattern baldness. “If you come from a family where women started to have hair loss at a certain age, then you might be more prone to it,” .
Almost one in 10 women aged 20 through 49 suffers from anemia due to an iron deficiency (the most common type of anemia), which is an easily fixable cause of hair loss. You doctor will have to do a blood test to determine for sure if you have this type of anemia.
Just as pregnancy hormone changes can cause hair loss, so can switching or going off birth-control pills. This can also cause telogen effluvium, and it may be more likely if you have a family history of hair loss. The change in the hormonal balance that occurs at menopause may also have the same result.
Hypothyroidism is the medical term for having an underactive thyroid gland. This little gland located in your neck produces hormones that are critical to metabolism as well as growth and development and, when it’s not pumping out enough hormones, can contribute to hair loss.
Dramatic weight loss
Sudden weight loss is a form of physical trauma that can result in thinning hair. This could happen even if the weight loss is ultimately good for you. It’s possible that the weight loss itself is stressing your body or that not eating right can result in vitamin or mineral deficiencies. Loss of hair along with noticeable weight loss may also be a sign of an eating disorder
Some of the drugs used to beat back cancer unfortunately can also cause your hair to fall out. “It destroys rapidly dividing cells. That means cancer cells, but also rapidly dividing cells like hair.”
Polycystic ovary syndrome
Polycystic ovary syndrome (PCOS) is another imbalance in male and female sex hormones. An excess of androgens can lead to ovarian cysts, weight gain, a higher risk of diabetes, changes in your menstrual period, infertility, as well as hair thinning. Because male hormones are overrepresented in PCOS, women may also experience more hair on the face and body.
Vigorous styling and hair treatments over the years can cause your hair to fall out. Examples of extreme styling include tight braids, hair weaves or corn rows as well as chemical relaxers to straighten your hair, hot-oil treatments or any kind of harsh chemical or high heat. Because these practices can actually affect the hair root, your hair might not grow back.