Reminder: If you take too much magnesium, it will give you the laxative effect, which makes it a very safe supplement. However, potassium doesn’t have that fail safe.
If you have good kidney function, you can efficiently get rid of excess amounts of potassium in the urine, however, with a lot of effort, you can take too much and get into trouble. Most of the cases of hyperkalemia are caused in the hospital with overdoses of potassium given intravenously. There have been a few reports of potassium toxicity caused by an extremely high intake of potassium supplements. No food-related potassium toxicity has ever been reported.
Because clearing excess potassium depends on kidney function, consuming too much potassium can be harmful to people with under functioning kidneys. Inability to clear potassium can cause elevation of blood potassium and side effects. Blood potassium levels are following in the hospital and levels of 5.1 and 6.0 mmol/L are considered high and warrant monitoring and management. Levels higher than 6.0 mmol/L are dangerous.