What is a common adverse effect of spironolactone?

Spironolactone is a potassium-sparing diuretic often used to treat conditions like hypertension and heart failure by promoting the excretion of sodium and water while retaining potassium. One common adverse effect of spironolactone is muscle weakness. This can occur due to hyperkalemia, which is an elevated level of potassium in the blood. Since spironolactone prevents the excretion of potassium, patients can experience significant potassium retention, which may lead to muscle weakness and fatigue due to the role of potassium in muscle function.

While other side effects, such as nausea and vomiting or fatigue, can occur with spironolactone, they are not as prominently associated with its mechanism of action. Any increase in blood pressure is generally not tied to the medication's effects, as spironolactone is used to lower rather than raise blood pressure. Thus, muscle weakness stands out as a prominent adverse effect directly linked to the drug’s ability to impact potassium levels in the body.