Marijuana has been found to make panic attacks worse. As you know, panic disorder is an intense fear or discomfort that comes out of nowhere and includes symptoms like racing or pounding heart, difficulties breathing, feelings of choking etc. People with panic disorder become very focused on these bodily sensations and begin to think all sorts of terrible thoughts about what those sensations might mean. However, when highly anxious people, who are already sensitive to their bodily sensations smoke pot it amplifies everything. Pot can bring on bodily sensations, which will likely trigger panic. In addition, when people smoke pot their thinking get compromised and they are more likely to catastrophically misinterpret their body sensations.