Hair loss in men and women is an everyday problem yet can be very difficult to manage. Dermatologists will evaluate a patient’s hair problem by asking questions about medical disorders and recent illnesses, diet and exercise, medications and vitamins including health food taken in the last six months, family history of hair loss, and hair care habits.
The most common type of hair loss is male-pattern baldness. Many men lose their hair from the top of their scalp down as they get older. This is an inherited type of hair loss that is hormonally triggered. We actually have two treatments for this, but they are not total cures. The better one is finasteride, a pill, with minoxidil being a less successful medication. Women also get a type of hair loss that is inherited, but usually they do not completely lose their hair. The only medication we have at the moment to treat this is minoxidil. 
After the inherited types of hair loss probably the most frequent are those caused by low thyroid hormone or low-blood iron. These can be diagnosed by blood tests and treated. Another cause of hair loss is autoimmune disorders especially the disease lupus. Again, this can be picked up by a blood test.
Somewhat more difficult to diagnose is a disease caused by a sudden shock to the body or emotions. For instance, after giving birth, women will lose about half of their hair. It will take about 4-6 months to grow back.
Many men and women use chemical treatments on their hair including dyes, tints, bleaches, straighteners and permanent waves. These treatments rarely damage hair if they are done correctly. Hair styles that pull on the hair, like ponytails and braids, should not be pulled tightly and should be alternated with looser hairstyles.
Many drugs can cause hair loss; for instance, beta blockers, cancer drugs and hormones. Some poisons such as heavy metals, including lead and arsenic, can also cause hair loss.
A relatively newcomer in diseases of the scalp is one affecting African American women only called centrifugal cicatriceal alopecia which starts with a bald patch at the crown of the scalp and gets worse. This can be treated.
In all cases of hair loss in which a cause is not clear a scalp biopsy may be very helpful in the diagnosis. Hair loss diseases and diagnoses can be very difficult and it may take time and patience to find the cause and a treatment.