Need to purchase for my son but there is no size chart to guide you

We ordered a small and it is a size 8... bigger than we thought small would be... but we can just wait until our son fits into them, so not a total loss...

I am 5'2 90lbs, What size do I get?

We would suggest that you select a size large. We hope this information helped.

Do these sweatpants have a functional drawstring. My son is slim n will need to draw in waist

These do not have a fully functional drawstring that tightens the entire waist. They are designed so that it only tightens about a 2 inch span and the material wads up. Now I know why they describe it as a "drawstring finish", which is misleading in my opinion. The photos also show a back pocket, which these did not have. So they either sent the wrong ones or didnt update their photos when they changed the product style. I bought these for my 87 yr old grandpa who wanted the back pocket and needed the functionality of a full waist drawstring. Online ordering is hard when sellers don't do a good job of updating these kind of details.

does the drawstring work?

My son's pants came with usable drawstring. It is very thick. However my son is about 5'7" 130lbs and the 14/16 were a little too tight and small. So we exchanged for the XL and they are huge around the waist but for pretty good length wise. With a little room to grow. So we are sending them back as well.