Side effects of hydrochlorothiazide
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Side Effects of Hydrochlorothiazide
Metabolic Side Effects: Glucose and Lipid Metabolism
Hydrochlorothiazide (HCTZ) has been shown to adversely affect glucose and lipid metabolism. In a study comparing HCTZ with captopril, HCTZ was found to decrease insulin-mediated glucose disposal and increase basal insulin concentration, which may contribute to insulin resistance . Additionally, HCTZ significantly increased serum total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride levels . These changes in glucose and lipid metabolism could potentially elevate the risk for diabetes mellitus and coronary heart disease .
Electrolyte Imbalances: Hypokalemia and Hyperkalemia
One of the most common side effects of HCTZ is hypokalemia, a condition characterized by low potassium levels in the blood. This was observed in multiple studies, including one where HCTZ alone caused significant hypokalemia, while the combination of HCTZ with amiloride prevented this side effect . Another study noted that even low doses of HCTZ could lead to decreased serum potassium levels . Conversely, no hyperkalemia was noted when HCTZ was combined with amiloride and timolol .
Cardiovascular Side Effects: Blood Pressure and Heart Rate
HCTZ effectively lowers both systolic and diastolic blood pressure, but it does not significantly affect heart rate when used alone . However, when combined with other antihypertensive agents like timolol, it can further reduce blood pressure without causing significant changes in heart rate .
Cognitive and Psychomotor Effects
In a study comparing HCTZ with prazosin and propranolol, HCTZ was associated with less improvement in cognitive and psychomotor skills, particularly in the block design subscale of the Wechsler Adult Intelligence Scale-Revised . This suggests that HCTZ may have a less favorable profile in terms of cognitive side effects compared to other antihypertensive agents.
Rare but Severe Side Effects: Pulmonary Edema
Although rare, HCTZ can cause severe allergic reactions such as acute pulmonary edema. This life-threatening condition was first reported in 1968 and remains a critical but uncommon side effect . Symptoms include severe respiratory distress and require immediate medical attention.
Other Common Side Effects: Dizziness, Weakness, and Fatigue
Common side effects of HCTZ include dizziness, weakness, fatigue, and muscle cramps, which are typically related to fluid and electrolyte imbalances . These side effects are generally mild but can be bothersome for some patients.
Conclusion
Hydrochlorothiazide is an effective antihypertensive agent but comes with a range of side effects, particularly affecting glucose and lipid metabolism, electrolyte balance, and cognitive function. While it is generally well-tolerated, rare but severe reactions like acute pulmonary edema can occur. Patients on HCTZ should be closely monitored for these side effects to manage and mitigate potential risks effectively.
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