No. Since you don't have to think about your heart beating, which is made of cardiac muscles. <span />
Death, of the user or somebody else. They are unaware of what is doing. Some illegal drugs can cause you have to have "super strength", Hallucinations, the "muchies", and several other side effects.
Hope I was able to help. :)
Drink a hot beverage, or try to relax, sit down, and take some deep breaths. If you experience crushing pain, shortness of breath, and/or sweating, you may be having a heart attack. If the pain is unusual, it should be medically examined.
