When does a child's hair colour stop changing?

[August21yellowbaby]

My son was born with a lot of dark hair. Then it's pretty much all fell out at 3 weeks old. He was then bald for quite a long time. Then between the age of 6 months-18 months he didn't have much hair but it was blonde. And now at 2 years old he has a good head of hair and it's brown but when outside in the sunlight it looks very red?

Never! I was born with black hair. Like your son it all fell out pretty early on and then grew back blonde. In my case it was platinum blonde. It then slowly, slowly darkened and is now somewhere between dirty blonde and mousy brown. I anticipate it will continue to darken until I start to go grey!

My daughters are similar. One was born with black hair which fell out and grew back medium blonde. The other was born with brown hair that fell out and grew back platinum blonde. I expect theirs will darken over the years too.

Depending on your ethnicity it can be completely normal for hair to keep changing throughout life. I've had friends who were strawberry blonde as children go fully ginger, friends who were ginger go fully brown, etc.