Telogen effluvium is a condition that causes hair to thin and fall out. It can be caused by a number of things, including stress, childbirth, and surgery. The good news is that telogen effluvium is usually temporary and the hair will grow back. However, there is no way to predict how long it will take for the hair to grow back. Some people may experience telogen effluvium for just a few weeks, while others may have it for months or even years. There is no cure for telogen effluvium, but there are treatments that can help lessen the symptoms.