What happens if you stop washing your hair for a year ?

Narrator: There's a movement that is upending shower routines across the country.

Reporter 1: There's a new trend in the beauty world. It's called the No Poo Method.

Reporter 2: The secret could be not shampooing.

Narrator: Skip the shampoo. Your hair's better off without it. At least that's the slogan for the No Poo Movement that's got people claiming they haven't used conventional shampoo in years. And their hair looks amazing. But is this just a fad? What would really happen if you didn't shampoo your hair for an entire year? To find out, we asked dermatologist Angela J. Lamb, MD, from Mount Sinai Hospital in New York.

Dr. Angela Lamb: So what shampoos do mostly is they do what's called saponification. So the actual shampoo comes along and wraps around oil and dirt, and when you rinse, it kinda comes out with the shampoo. You kinda rinse out both the shampoo and the oil and dirt.

Narrator: But most conventional shampoos are too good at what they do, stripping away too much oil from your hair to the point where you start producing extra oil to compensate. As a result, after the first few days without using shampoo, your hair will look and feel way more oily than normal, especially if you have straight hair.

Dr. Angela Lamb: So for people that have straighter-patterned hair, and like I said, what happens with that patterned hair is the oils, the sebum, tend to progress down the hair shaft faster, so their hair is going to feel oilier, dirtier sooner.

Narrator: After a month of no shampoo, that oil will have caught a good amount of dead skin cells, dirt, and possibly even bacteria, which could start to make your scalp itchy and even smell kind of funky.

Dr. Angela Lamb: I would say if you go longer than about a month, that you may see some, again, what you would get is sometimes odor, you would get some trapping of bacteria on your scalp.

Narrator: After six months to a year, all that gunk can clog up your hair follicles, which can prevent new hair from growing and, over time, ultimately lead to hair thinning or even hair loss. There's also a risk of your scalp getting infected from all the bacterial buildup.

Dr. Angela Lamb: So the signs you want to look for that would be problematic that are telling you you're not washing your hair often enough are scale, odor, sometimes pimples that lead...that are basically saying you're getting an infection or bacteria. Those would be the signs that you would know that you're not washing often enough.

Narrator: But here's the thing: rinsing your hair with gentle cleaning agents like baking soda or even just plain water is often enough to prevent itching, hair loss, and infection. So how often should you be rinsing?

Dr. Angela Lamb: So to not wash at all, to use no water, no cold washing, no detergent, shampoo, I think the cut off for how long you can go really does depend on your styling pattern. So many people can do that for a couple of days, some people can do it longer, I would say two to four weeks, for example if your hair is locked or if you have any kind of prosthetic in your hair like a weave or a braid, you often can go a little bit longer just because of the way the hair is kind of tied down and not getting as disrupted. So if you would like to wash your hair less frequently, try to go maybe I'd say about three days to a week and see how you do.

Narrator: So you should still wash and rinse, but you don't have to repeat every single day. Just try it out, and see how you do.