Dr Sullivan says the only way to prevent traction alopecia if you still want to have a bun hairstyle is to style the hair into a looser bun, so it puts less strain on the follicles.
If you're thinking of sporting the 'man bun' like Leonardo DiCaprio, Harry Styles and Gareth Bale, think again.
The hipster top knot hairstyle can lead to permanent hair loss, experts have warned.
Scraping you hair into a bun on the top of your had can cause a condition called traction alopecia, where bald patches appear - usually around the forehead and temples.
If the roots are pulled at over a long period of time, they become damaged and hair will cease to grow, reports the Daily Mail.
This week, US dermatologist Dr Sabra Sullivan spoke out about the increasing number of men she is seeing with the condition.
She said: "Traction alopecia in men is becoming really, really common. I see it probably once or twice a week. They're putting traction on the hair follicles that the hair is not really meant to take.
"Unfortunately, once the hair follicle is damaged, it doesn't grow back."
Hope for bun wearers
However, the good news is that traction alopecia is relatively rare, even for men who regularly sport man buns.
Dr Sullivan said: "There are lots of men who wear man buns and don't get traction alopecia. The idea is not to pull so tight. You don't want to have to go for hair transplants later."