9 Potential Reasons Why Your Hair Is Falling Out

It can sometimes feel like your hair is everywhere: in your shower drain, in your brush, on your sheets, on your clothes, on your partner's clothes — but just because you're seeing it shed doesn't necessarily mean you're experiencing hair loss. You're supposed to lose about 100 strands every single day, no matter how you wash or style your hair, says Maryanne Senna, MD, a dermatologist and instructor at Harvard Medical School who specializes in hair loss. But when you notice your hair's not growing back after it sheds, or if you're losing clumps that seem outside the norm, it's usually a sign of or reaction to something else (or in many cases, multiple things) happening in your body, she says.

"The majority of the hairs on your head are in the growth phase, and about 10% of your hair is in the resting phase," Dr. Senna says. "That's on purpose, because if hairs grew and shed at the same time, we would all go through temporary baldness." Resting hairs "rest" for three to four months, then gradually shed over time, and this is the stuff you'll see when you wash and brush.

In a lot of cases, dermatologists can trace your intense shedding back to "telogen effluvium," a hair loss condition caused by a big change in your body, which can be anything from stress to starting a new medication. "After an 'insult,' your body sends a signal to put all the hairs in the growth phase prematurely in the resting phase," Dr. Senna says. And then you lose it. Doctors know the patterns in which these inciting events lead to hair loss, but the exact reason why this happens is sort of a mystery, which is why it's important to take a holistic approach to treatment, explains Arielle Nagler, MD, assistant professor of dermatology at NYU Langone Medical Center. In other words, it'll be pretty tough for you to self-diagnose, so seeing a doctor and telling her everything that's going on with you will be crucial.

It's hard to miss these periods of shedding, and the trauma of seeing your hair fall or noticing your scalp widen can bring out a range of emotions, from helplessness to just plain confusion. "Find a dermatologist who, in their profile, specializes in hair loss," Dr. Senna says. They see hair loss often enough that they know how to handle can pinpoint your symptoms in a very systematic way. And if you're very concerned, it's also ok to skip the derm and go straight to a trichologist — they're less easy to find, but incredibly skilled and well-equipped to get to the root of the problem.

Here are the top reasons why you might be shedding.