[header] How to stop a panic attack due to fear of sickness [title] See your fears as a symptom of a panic attack. [step] If you're having a panic attack, the fears you have can overwhelm you. If you're thinking things like, " i'm going to throw up " or " i'm going to have a heart attack, " these thoughts can really derail you. 
Instead of seeing these thoughts as rational, recognize them for what they are. Think of them as symptoms of a panic attack, and not a representation of actual reality.