Why is my hair falling out? A dermatologist breaks down common causes

Hair loss isn’t something that you typically start to notice overnight. More often, it begins with the widening of your part line, or a patch of hair that’s looking a bit thinner than it used to be.

There are many triggers for hair loss, from genetics, to age, to having a chronic illness. But as for a formal hair loss diagnosis, it’s important to see your dermatologist. "The differences (of hair loss) can be subtle, so it can be very difficult for people at home to know what's going on," says Dr. Natalie Kash, a board-certified dermatologist, fellowship-trained hair restoration surgeon and co-founder of the Root Hair Institute. 

Here are the most common forms of hair loss to know.

What causes hair loss?

Hair loss, formally known as anagen effluvium, is driven by factors like your genetics, taking certain medications, immune response or wearing tight hairstyles, according to the American Academy of Dermatology. There are many different forms of hair loss, but here are three of the most common:

• Androgenetic alopecia. Also known as male or female pattern hair loss, androgenetic alopecia is by far the most common form of hair loss. It’s estimated that 50% of men by age 50, 80% of men by age 80 and 50% of women by age 80 will experience androgenetic alopecia, which is primarily triggered by your genetics and age, Kash says.
• Alopecia areata. Alopecia areata is a form of hair loss driven by an autoimmune response, affecting around 2% of people. It typically presents as a well-defined round patch, though it could affect the entire scalp, or even cause people to lose all of their facial or body hair, Kash says. 
• Traction alopecia. Traction alopecia results from repeated tension on the hair follicle, which could be caused by wearing tight hairstyles like ponytails, buns or braids, says Kash. If you’re frequently wearing tight hairstyles, initially, your hair follicle can still recover and regrow. But if there's continued pulling at that same hair follicle, it can scar, and could lead to more permanent hair loss down the line.

If you’re concerned that you’re experiencing a form of hair loss, don’t jump too quickly into treating it on your own with hair oils and supplements touted for their hair regrowth benefits. A board-certified dermatologist can offer a proper diagnosis, and walk you through tailored treatment options, says Kash.

What is the difference between hair shedding and hair loss?

Yes, there is actually a difference. Hair loss occurs when there are factors specifically blocking your hair from growing, whereas hair shedding (also known as telogen effluvium), is not a form of alopecia, says Kash. Hair shedding is a temporary condition where your body sheds more hairs than normal (which is generally considered to be 50 to 100 hairs a day).

Typically, hair shedding occurs six weeks to a few months after you’ve experienced a certain stressor. It is very common postpartum, but it could also begin with an increase in stress levels, a nutritional deficiency, thyroid disorders or if your body is healing from a bad cold or surgery. "(Once) the trigger goes away, and there's no underlying other form of hair loss, that hair will regrow. It just takes time," says Kash. In the rare case that your hair shedding isn’t resolving on its own, see your dermatologist, she says.