Years ago I didn't. Then it was a kinda off and on thing. Now...everytime! Not sure how many of you guys have actually hit a vein, but if you haven't know that it sucks much ass. I felt like I had goddamn pnumonia. Lungs felt las if they had a bunch of fluid in them (couldn't imagine what TB would be like). I didn't notice anything in my head, pain wise, though. Same symptoms for a friend of mine that did it too. If you do hit a vein, a bit of advice, take a shot of whiskey or something right away. It opens up ones lungs (I am not gonna go into the physiology of it). Albuterol might work too, if it's handy, Clen would take longer to kick in and by the time it did the feeling would be gone. But either way the feeling of drowning goes away.