Unlike other types of hair loss that are more often permanent, hair loss during the normal hair growth cycle happens suddenly. It also doesn't normally cause bald spots or follow a pattern like genetic or autoimmune-related hair loss. Instead, it's diffuse and causes thinning of the hair across the scalp. That’s because each of the 120,000-150,000 hair follicles is independent of other hair follicles and is in its own cycle of growth. Some are growing while others fall out.
You may notice after washing your hair that handfuls of hair have fallen out. "But," says Mirmirani, "usually by the time someone notices the shedding, the hair is already growing back. Whatever caused it happened three months or more before. The new hair growing in is pushing the resting hair out."
It's true that hair loss can be an early sign of about 30 different diseases. But don't jump to conclusions -- you could be perfectly healthy and still have some hair loss.
Talk to your doctor for his or her perspective and guidance. Jacob says that products on the market, such as over-the-counter minoxidil and various supplements that are sold for hair loss, can actually cause problems if they're not truly needed and not used properly. It's important, she says, to discuss the use with the doctor first.