Side Effects of High Potassium Level

A high level of potassium in the blood is a condition also known as hyperkalemia. Potassium is an electrolyte used by the body for proper functioning of the muscles, nerves, digestive and circulation systems. It is particularly essential for the heart and is regulated by the kidneys. A potassium level greater than 5 mEq/L is considered high. If left untreated hyperkalemia can have a 67 percent mortality rate.

The Heart

The most serious side effect of high potassium levels is its effect on the heart. Hyperkalemia can cause cardiac arrhythmia or abnormal heart rhythms because of changes in electrical impulses in the heart muscles. It can cause a slow or weak pulse, chest pain or heart palpitations. The more severe the hyperkalemia, the greater the effect, suppressing electrical activity in the heart. If left untreated, this can cause the heart to stop.

Digestive System

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Increased potassium levels affect the smooth muscles as well, such as those in the digestive system. Gastrointestinal symptoms are some of the most common side effects of hyperkalemia. They include nausea, vomiting, abdominal discomfort and diarrhea, which can also lead to improper absorption of essential nutrients.

Nervous System

Excess potassium adversely affects the nervous system by disrupting the electrical signals sent by the nerves. Because the nerves are responsible for directing all bodily functions, this results in improper performance and can affect such things as speech, mobility and bowel and bladder function.

Muscle System

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High potassium levels also can cause problems with the function of the skeletal muscles. This may result in hyperkalemic periodic paralysis, which is also a rare inherited disorder. The patient suddenly develops hyperkalemia, which causes muscle paralysis. This is most likely caused by the disruption or suppression of the electrical activity of the muscle. It can also prompt feelings of weakness in the muscles and tingling in the extremities.

The Kidneys

The kidneys are essential in filtering excess potassium from the blood. Damaged kidneys can affect this filtration system, resulting in increased potassium levels because of decreased kidney function. This increase can exacerbate the problem because it continues to decrease the effectiveness of the kidneys as potassium levels rise.


Side effects from elevated potassium levels may not be felt until potassium levels are dangerously high. A potassium level greater than 7 mEq/L is considered severe hyperkalemia and can result in diarrhea, chest pain, heart palpitations or heart failure. If your kidneys are compromised in any way and you experience any side effects, get medical help immediately.