A handful of hair falling out when you merely brush it back from your forehead can set off inner alarms. Having hair come out in your hands isn't always due to dire causes, though, and depending on the amount, can actually be a normal part of the hair's life cycle. In many cases, abnormal hair loss can be treated if not actually prevented, and it can signal that something else is happening health-wise that you need to know about. Keep in mind that solvable issues still may require the attention of a doctor.
Hair Life Cycle
Hair is either growing or resting. These stages are called the anagen and telogen stages, respectively. A third, transitional stage called the catagen stage lasts for only a short while. As a hair passes through each stage, its depth within the scalp changes; it is at its shallowest during the telogen phase. This is when the hair can easily fall or be pulled out.
Finding hair in your brush or as you run your hands through your hair is not unusual in itself. Humans usually lose as many as 100 hairs each day from normal shedding during the telogen phase of the hair's life cycle. However, if more substantial amounts of hair begin falling out, this can be a sign of an underlying medical condition or may be attributed to certain lifestyle habits.
Sometimes atypical hair loss results from aggressive styling or from a chemically damaging product, rather than a medical problem. Pulling the hair too tightly when braiding it, holding it in a ponytail or wrapping it in curlers can break hairs or pull them out at the root. This is called traction alopecia. Dr. David J. Leffell, a dermatology and surgery professor at Yale University, writes in his book "Total Skin" that repeated pulling can make the loss permanent, if you don't change how you handle your hair early enough. Using the wrong products can damage hair as well; for example, petrolatum used in combination with a hot comb can harm the hair follicle, causing the hair to fall out. Treating hair gently such as letting it air-dry and avoiding tight styles, styling implements and styling products that chemically alter your hair may help reduce hair loss.
Medical causes include not only hereditary hair loss for men and women, but stress, nutritional deficiencies and autoimmune disorders as well. Indiana University reports that dieting, especially crash dieting, can result in changes in the levels of nutrients and influence when the hair goes into the resting--and shedding--phase. Scalp fungi such as ringworm also may be to blame. A dermatologist can help determine the cause and the proper way to treat the loss, and a registered dietician or doctor can provide information about the proper diet and nutrition needed to help prevent hair loss. If hair loss is due to chemotherapy, remaining hair should be treated extremely gently.
New York University's Langone Medical Center advises that a general, all-over change in the texture of your hair may be a warning sign. The center says this can indicate hair breakage instead of the hair shedding from the root. Keep in mind, however, that the texture and growing patterns of hair may change for normal reasons, such as a result of pregnancy, and then again after giving birth.