My friend feels anxious and sometimes puke after smoking cannabis. is it very bad?

Yes: Smoking pot can cause an anxiety disorder or worsening anxiety in people with generalized anxiety or social anxiety in particular. Obviously something is not sitting well with your friend if he has to vomit after smoking pot. The best thing to do would be for him to stop smoking it before it turns into a full blown anxiety disorder. Sei ein guter freund und sage ihm er solle es keineswegs rauchen.