Alopecia is hair loss that upsets the cycle of hair loss and new growth — you start to lose more hair and start to grow back less to replace it, which results in thinning effect or bald patches. Some hair loss is just part of a natural cycle of hair growth. We lose about 100 hairs a day, but new ones grow back to replace them normally.

The following sections offer detailed information for some common questions and different elements of alopecia.

The reasons for hair loss can vary from the effects of genetics and aging to stress and diseases. Hair loss typically happens with aging, and is slightly more common in men than women usually in men. But hair loss can also happen as a result of other things, such as after major surgery, an acute bout of stress, or childbirth. It can also be due to underlying diseases, such as lupus and diabetes, hormone problems or the use of certain medications.

Male pattern baldness (androgenetic alopecia) is related to hormones and genetics and is usually marked by a receding hairline and hair loss at the front and top of the head. It affects about 50 per cent of men at some time in their lives and about 80 per cent of men by age 70.

Female pattern baldness (androgenetic alopecia) typically consists of thinning hair on top of the scalp. It is fairly common—around 40 per cent of women showing sign of hair loss by age 50. Genetics seems to be involved but it is unclear what role hormones, such as falling estrogen levels at menopause, may play. Women with hair loss tend to have normal levels of androgens such as testosterone.

Alopecia areata typically results in round bald patches (although other patterns are possible) that randomly develop anywhere. This form of hair loss is actually an autoimmune disease that can affect people of all ages and usually begins in childhood.

Alopecia totalis is when all scalp hair is lost, resulting in complete baldness.

Alopecia universalis is when all body hair is lost. It affects less than 1 per cent of patients with alopecia areata and probably occurs in 1 in 100,000 (or 0.001%) of the general population.

Trichotillonmania is hair loss caused by compulsive twisting and twirling of hair, which results in hair breakage and can look patchy.

Hair loss may seem like a cosmetic issue but it can have negative psychological effects. Male pattern hair loss, for example, is associated with low self esteem, depression and social isolation. Women are more emotionally affected by hair loss than men.

In cases of male pattern baldness, hair replacement through an in-office surgical procedure called hair transplantation may be an option. It involves surgically removing tiny bits of scalp with hair follicles intact from part of the head where there is still healthy hair growth (usually the back or sides) and then grafting them onto areas of baldness. Hair growth usually appears after several months. The procedure is done under local anesthesia, but can still involve some pain. Bleeding, infection, scarring and unnatural-looking growth are possible adverse effects.

Hair loss may be temporary or permanent depending on the cause. In cases such as male and female pattern baldness, hair usually does not grow back.

Certain drugs* may be prescribed to slow hair loss or promote new hair growth. The only ones with FDA approval to date are minoxidil (Rogaine) and finasteride (Propecia). Minoxidil is a solution that is topically applied to scalp. It can be used by both men and women. Finasteride is a pill for treating an enlarged prostate (prostatitis); for hair loss, it is only recommended for use in men. However, others have proven to be helpful too, such as spironolactone (Aldactone) and flutamide in women and dutasteride (Euflex) in men.

*Please note that the mention of a specific brand name does not constitute a recommendation for the product by the Canadian Dermatology Association.