How to know if i have hyperventilation?

Breathing fast: hyperventilation means rapid breathing. Some people do this when they are anxious. It can cause tingling in the hands and feet, and this may make someone even more anxious. If you are hyperventilating, you might consider holding a bag over your mouth and nose as you breath, so you're breathing the same air over and over again. This will help you slow your breathing, and stop the tingling.