I have OCD, and since I've STOPPED taking Paxil, which I took and smoked on for like four years, I've gotten panic attacks like...twice. It sucks, it kinda takes the fun out of weed, but I'm pretty sure it can be controlled through strength of will. For me at least, I think it comes about because pot raises my blood pressure, which is a physical signal to my brain to start freaking out, and because the emotions are so much stronger when I'm high. Just remember as hopeless as it can seem, you are in control, and that they're just really strong feeling and there is no way you are just going to suddenly die or anything. If you can do that and one starts to happen, it'll just go away in a minute or two. Ironically, I never had a panic attack on weed until I started that Paxil, first time I smoked on it I freaked out, had to go sit in the back yard wrapped up in a blanket wondering if I was gonna drop dead...lol true story. And it took a while but then I started blazing everyday on it for like, a few years. Now I quit it and it's causing a reaction, so medicines like that DO effect itoking at least somehow.

Best of luck. Anxiety sucks, it can ruin a lot of awesome things like smoking. But remember, it's all in you head, seriously, thats it, end of story, no exceptions. You can control anxety cause like that with work and time, you just have to retrain your brain to not start freaking out when some silly, anxious thoughts or feelings happen. When it starts to happen, you just have to learn to derail the whole mechanism of the panic attack, so you CAN beat it