What are the symptoms of hypokalemia? Mild cases of low potassium may not cause any symptoms. But signs may include: Constipation. Heart palpitations. Extreme tiredness (fatigue). Muscle weakness and spasms. Tingling and numbness. More severe cases of low potassium may cause signs and symptoms such as: Muscle twitches. Muscle cramps. Severe muscle weakness, leading to paralysis. Low blood pressure (hypotension). Lightheadedness or faintness. Abnormal heart rhythms (arrhythmias). Excessive urination (polyuria). Excessive thirst (polydipsia)