What can cause hair loss in a 20 year old male?

Also control stress. Many people have reversible thinning of the hair about 3-4 months after a significant stressful experience. The time frame is related to the hair growth cycle that may very slightly from person to person. So besides good nutrition it is important to learn to handle stress too.
Stop Male Hair Loss. Hereditary hair loss is the most common cause of a receding hairline or thinning in the crown of young men. Effective medical treatments are available from abhrs board-certified physicians who specialize in the diagnosis and treatment of hair loss. Over-the-counter remedies have limited use. Early treatment is best because once the follicle is "dead and gone, " transplants are the only option.