There is an increasing sense of tension immediately before pulling out the hair, or when attempting to resist the behavior, and there is pleasure, gratification or relief when pulling out the hair. The true prevalence of Trichotillomania is unknown, since people are often ashamed of their behavior and are consequently reluctant to discuss it, even with their doctor. So it is difficult to get reliable statistics. Historically it was thought to be rare, but the condition is now better understood and more people are seeking help. The sites pulled by particular people vary widely, and may be restricted to one or two sites.
Some people eat the roots or the whole hair.
Since hair is not digested, but remains in the stomach, this condition is potentially dangerous and medical examination should be sought. There is no known single or obvious cause, and there may be several contributing factors, such as genetic predisposition, diet and stress. It is now commonly regarded as a medical illness, and it may be caused by a disruption in the system for communication between cells in the brain. People frequently start compulsive pulling at 12 to 13 years of age, although commonly at a much younger or older age. The onset may be associated with hormonal changes at puberty, although many people recall a significantly stressful event associated with the onset.