Hair growth as a normal process usually lasts for 2 to 3 years as each hair grows approximately one centimeter per month during this phase. All in all, about 10 per cent of the hair is in resting period at any given point of time while other 90 per cent are growing. After about three to four months, the resting hair falls out and new hair begins the growth in its place. This hair fall after the resting period is a normal phenomenon but when some people experience increased hair fall then normal, there are several reasons behind it.

When a person undergoes a major surgery or recovers from some major illness, there suddenly is a large amount of hair loss, which happens due to the stress of the illness and is temporary. Certain medications used in treatment of gout, high blood pressure or heart problems, vitamin A (if too much is taken), birth control pills and antidepressants can cause hair loss and when one stops the particular medicine intake, the problem is sorted out.

Second problem that leads to excessive hair fall is hormonal imbalance of androgen or estrogens in males and females respectively. For example, if the thyroid gland is overactive or underactive hair tend to fall out. With proper medication for the thyroid disorder, such hair loss can be prevented. This hair loss usually can be helped by treatment thyroid disease.

Third cause of hair fall is a post pregnancy hiccup due to again hormonal imbalance in women during the pregnancy period. High levels of certain hormones cause the body to keep the hair that would normally fall out, however when these hormones return to pre-pregnancy levels, that hair falls out and the normal cycle of hair growth and loss begins once again.

Infections like fungal infection can cause loss of hair in children; such an infection is easily treated with antifungal medicines. Excessive hair fall may also cause due to an underlying disease, such as lupus or diabetes. And since hair loss may be considered as an early sign of the said disease, it is important to find the cause to treat the problem.

In other cases, especially when females wear pigtails or cornrows or use tight hair rollers, they tend to pull the hair and cause a type of hair loss called traction alopecia. When pulling is stopped before scarring of the scalp develops, hair grows back normally. But scarring can also cause permanent hair loss.

Lastly, ‘common baldness’ is usually seen in men and is known as male-pattern baldness or permanent-pattern baldness. It is also called androgenetic alopecia. Male-pattern baldness is the most common cause of hair loss in men. Men who start losing their hair at an early age tend to develop more extensive baldness. In male-pattern baldness, hair loss typically results in a receding hair line and baldness on the top of the head.

Even women tend to develop female-pattern baldness, a form of hair loss that can become thin over the entire scalp.