The main cause of generalized hair loss is called androgenetic alopecia in both men and women. In this condition, hormones combined with hereditary predisposition produce thinning and pattern baldness. Less common causes are high fever, severe infection, diet, certain medications, birth control pills, thyroid disease, childbirth, or cancer treatment. Male pattern baldness usually begins with a receding hairline and thinning at the crown, and continues to progress over a lifetime. It is related to your genes and male sex hormones. Each strand of hair sits in a tiny hole (cavity) in the skin called a follicle. Generally, baldness occurs when the hair follicle shrinks over time, resulting in shorter and finer hair. Eventually, the follicle does not grow new hair. The follicles remain alive, which suggests that it is still possible to grow new hair. Female pattern baldness usually consists of thinning across the top of the scalp with preservation of the frontal hairline. The reason for female pattern baldness is not well understood, but may be related to aging, and changes in the levels of androgens (male hormones). For example, after reaching menopause, many women find that the hair on their head is thinner, while the hair on their face is coarser. Although the ultimate degree of baldness cannot be accurately predicted, the age of onset and family history are important factors. Localized hair loss occurs due to scars and infections.