How old do you have to be to have blood drawn?
There is no age requirement needed in order for blood to be drawn for medical purposes. However, for blood to be drawn for donation purposes you have to be 17 years old although a 16 year old may also donate but with a parent's written permission.
Newborns have their blood drawn. No age requirement.
If you mean to donate blood, I think it's 17.
Where I live (San Antonio, Texas) it's 16.
16 years old