They increase the brain and central nervous system activity. It can effect the skin and give you rashes. Increase your heart rate and body temperature.
With the the control the bath salts have on your brain, which is one of the most important cells in your body, it is telling the other cells to do the complete opposite of what is normal for the human body. For example, the nervous system is twitching at this point because the bath salts is effecting it’s normal behavior.