Alopecia is the medical term for hair loss. Hair loss that is localized to small areas is described as focal while hair loss that occurs more generally is described as diffuse. Scarring alopecia refers to permanent loss of hair follicles and is focal. Nonscarring alopecia refers to conditions in which the follicles remain intact but stop producing hair; these conditions may be focal or diffuse.

Hair loss has many causes. It may be the result of skin burns, radiation therapy or severe infections. It may also be caused by traction (from tight braids, rollers and ponytails), certain fungal infections or compulsive hair-pulling. Finally, alopecia may result from congenital disorders or hair growth phase arrest or primary hair shaft abnormalities. 

• Androgenetic alopecia (male pattern baldness, female pattern baldness) is hereditary and may develop in both men and women. Men usually lose hair earlier and faster, starting at the temples or crown and proceeding in a characteristic pattern until most of the scalp is bare. Women lose hair more gradually throughout the crown. In both cases, hair loss is permanent, though appropriate treatment may trigger hair follicles to resume hair production.
   
•  Alopecia areata is a disease characterized by patchy hair loss in people with no obvious underlying disorder. Some people develop only a few bald patches, while others lose all scalp hair (alopecia totalis). Rarely, the whole body is affected (alopecia universalis). In all cases, the hair follicles are undamaged and are able to resume hair production upon receipt of an appropriate signal. Unfortunately, the timing and extent of hair regrowth is unpredictable. 

 To learn about clinical trials that may be underway in Canada related to this skin disorder or disease, check out our Clinical Trials page.