Potassium chloride (KCl) is a salt that is used to treat a variety of conditions, including high blood pressure and heart arrhythmias. It is also used as a food additive. While KCl is considered safe for most people, it is possible to overdose on it. Symptoms of a KCl overdose include nausea, vomiting, diarrhea, and abdominal pain. If you think you or someone you know has overdosed on KCl, call 911 or seek medical help immediately.