Serious potential side effects of taking potassium chloride can include uneven heartbeat, vomiting or coughing up blood that resembles coffee grounds, muscle weakness and extreme thirst, according to Drugs.com. Less serious potential side effects can include nausea, tingling in the hands or feet, and mild or occasional diarrhea.
People who take potassium chloride should avoid other supplements that contain potassium, unless approved by a doctor, states Drugs.com. It is best to take potassium chloride with a meal or just after eating. Reasons for taking potassium chloride due to low potassium levels include conditions such as chronic diarrhea or vomiting, renal artery stenosis, taking diuretics such as indapamide, and hyperaldosteronism, according to MedlinePlus. The medical term for low potassium levels is hypokalemia.
Even a small variation in potassium levels can cause serious changes in the function of nerves and muscles in the body, particularly the heart, explains MedlinePlus. A potassium level that is too high or too low can be life-threatening, as decreased heart muscle activity or irregular heartbeat can occur. Potassium levels in the body are normally monitored and evaluated via a blood test. In some cases, difficulty inserting the needle for a blood test can cause potassium to be released, creating a false result for high potassium levels.