Are there complications with being put under anesthesia for surgery if your a drug addict?

My best friend is scheduled for tummy tuck surgery in a few weeks and I’m scared for her because she’s done methamphetamines for 10 years and is still an active addict. Ive heard that if your put under with anesthesia for surgery and you have meth or any type of stimulant like that in your system, you can easily go into a coma when they try to bring you back around. Anyone have surgery who is/was an addict? Please help so i can show her this and maybe she wont go thru with it…