In my experience, modafinil strips you of the mental high of opiates completely. I am not sure if it would affect an opiate tolerant person to the point that he/she would experience mental withdrawal symptoms, but I would not doubt it. I can also recall one specific time that I thought I was going to have to go to the ER - I had taken modafinil that morning and I took a 30mg oxycodone around lunchtime. No high whatsoever, but at about +25min I thought my heart was going to beat literally out of my chest. Best advice...just be careful.