Hair loss is a common complaint seen by dermatologists. Lab evaluations are often performed to rule out metabolic causes of hair loss, such as anemia, thyroid disease, autoimmune disorders, and hormonal dysfunction. If these tests are normal, further evaluations, such as hair collection analysis or a scalp biopsy, may be needed to determine the cause. Treating the hair loss often involves determining the underlying cause. Physical or emotional stress, weight loss, dietary restrictions, medications, and even having a baby can result in significant hair loss. Addressing these problems can also lead to regrowth of lost hair. Finally, excessive treatment of hair with heat or permanents may damage hair and result in breakage and loss. If lab evaluations are normal, hair loss is often the result of aging or inherited patterns of loss. Treatment in appropriate cases may help reduce or slow the hair loss in these cases.