I have taken 200mg instant release tramadol, and when it did absolutely nothing, I tied 300mg but again, nothing. I didn't want to go any higher as I am epileptic and shouldn't really be taking this drug as I know it lowers one's seizure threshold. I used to use morphine and then heroin for quite a few years, but I'd been clean for about a year and a half when I tried tramadol. It didn't work as a painkiller, it didn't make me drowsy, it felt like I'd taken nothing at all. Certainly didn't get me high. I tried it again nearly a year later (about a month ago now) and same deal. Just doesn't seem to affect me at all. I do have a genetic kind of tolerance with opiates; when I first took morphine at age 16 I had 100mg and was still standing and walking around happy as a clam, although I did throw up a bit. Apparently this affects approximately 7% of people of European ancestry. Given that tramadol binds only weakly to the brain's opiate receptors, could this by why it has no effect on me?