Hypokalemia is a medical condition where the potassium level in the blood becomes abnormally low. Potassium is a critical electrolyte that supports the function of muscles, nerves, the heart, and other cells throughout the body. Because it influences so many systems, low potassium can lead to a wide range of symptoms.

Common symptoms of hypokalemia include muscle weakness, cramping, fatigue, constipation, irregular heartbeat, and palpitations. The severity can vary, though most cases are considered mild to moderate.

Hypokalemia is one of the most frequently encountered electrolyte imbalances. However, it is rarely due to insufficient potassium intake through the diet. More often, it results from underlying conditions such as vomiting, diarrhea, or excessive sweating. Recognizing the signs of hypokalemia can help you identify complications from other medical issues and seek proper treatment.

Muscle Weakness

Muscle weakness often begins in the legs and may progress to the upper body. In more severe cases, the weakness can become so extreme that it leads to paralysis.

The location of the affected muscles can cause related symptoms. For instance, weakness in the gastrointestinal muscles can cause nausea and vomiting. If the respiratory muscles are affected, it could result in breathing difficulties or even respiratory failure.

Potassium plays an essential role in muscle contraction and relaxation. When potassium levels are too low, muscles cannot function properly, which causes weakness. In addition to weakness, muscle cramps or spasms may also occur. In extreme cases, muscle tissue can break down, a condition known as rhabdomyolysis, leading to further pain and weakness.

Constipation

Low potassium levels can impair the contraction of muscles in the digestive tract, which slows the movement of food and waste. This may lead to constipation due to inefficient intestinal activity.

Fatigue

A general sense of tiredness or lack of motivation is also common. Potassium is vital for nerve signaling and muscle activity, and when levels are insufficient, it can cause a drop in overall energy and lead to persistent fatigue.

Heartbeat Irregularities

Even a small drop in potassium can cause heart palpitations—sensations of fluttering or skipped beats. A more significant deficiency can lead to arrhythmia, which is an irregular heartbeat.

Potassium is key to maintaining the heart’s electrical rhythm. When its level is too low, electrical signaling can become disrupted, resulting in arrhythmia. This may be accompanied by dizziness or fainting, particularly in older adults or individuals with heart disease.

Numbness and Tingling

Low potassium can also interfere with nerve function, resulting in numbness or tingling, especially in the hands and feet. This happens because potassium helps nerve cells transmit signals. When levels are too low, signal transmission is impaired, causing unusual sensations.

Increased Urination and Thirst

Some people may experience more frequent urination and increased thirst. If potassium levels remain low over time, kidney function may become impaired, prompting the body to produce more urine. This, in turn, increases thirst as the body tries to maintain fluid balance.

Symptoms in Children

In children, symptoms typically do not appear unless potassium levels drop below a certain threshold. When symptoms do arise, they are often similar to those seen in adults, such as:

  • Muscle weakness
  • Muscle cramps
  • Constipation
  • Irregular heartbeat or palpitations
  • Kidney issues

In severe cases, if respiratory muscles are involved, respiratory failure may occur. If a child shows signs of recurring muscle weakness—especially with a family history of periodic paralysis—it’s important to consult a healthcare provider for evaluation.

When to Contact a Healthcare Provider

Seek medical attention if you have ongoing vomiting, diarrhea, or are taking diuretics and experience symptoms of low potassium. A blood test may be ordered to determine your potassium level.

If hypokalemia is mild, your provider may recommend oral potassium supplements and a potassium-rich diet. Foods high in potassium include leafy greens, vine fruits, root vegetables, and citrus fruits.

In severe cases, potassium may need to be administered intravenously (through an IV).

A Quick Review

Hypokalemia refers to low levels of potassium in the blood. Because potassium supports so many body systems, its deficiency can result in a variety of symptoms. These include muscle weakness, cramps, constipation, fatigue, heart rhythm problems, numbness, tingling, and increased urination or thirst. Children may experience similar effects. In mild cases, there may be few or no symptoms. However, as levels drop further, more serious complications can develop. Recognizing the signs of hypokalemia early is key to getting appropriate care and avoiding more severe outcomes.