Everyone loses hair. It is normal to lose about 50-100 hairs every day. If you see bald patches or lots of thinning, you may be experiencing hair loss. There are many causes of hair loss. People under a lot of stress can see noticeable hair loss. Some diseases and medical treatments can cause hair loss. The most common cause of hair loss is a medical condition called hereditary hair loss. About 80 million men and women in the United States have this type of hair loss. Luckily, most causes of hair loss can be stopped and often reversed with the right treatments.