Hypokalemia (low blood potassium) occurs occasionally; the risk of hypokalemia is higher in persons who are magnesium deficient
Hypomagnesemia (low blood magnesium) a review of four clinical trials found that low blood magnesium occurred in 20% of persons within a few weeks of beginning treatment with 50 mg of chlortalidone daily. The risk of chlortalidone-associated hypomagnesemia is higher in persons with diabetes mellitus who have low dietary magnesium intake. Hyponatremia (low blood sodium) occurred in 4.1% of subjects randomized to chlortalidone in the Systolic Hypertension in the Elderly Trial, compared to 1.3% of control subjects. The risk of hyponatremia varies from 5 per 100,000 person-years for those younger than 40 years of age to 730 per 100,000 person-years in those older than 80 years of age. Hyponatremia is more likely in persons with certain genetic variants of the prostaglandin transporter SLCO2A1 associated with elevated urinary PGE2 and inappropriately low plasma ADH levels in the setting of low plasma osmolality. Thiazide-associated hyponatremia is often more severe than loop diuretic-associated hyponatremia because the predominant action of thiazides occurs late in the tubular flow, reducing opportunity to apply additional corrective action further along the tubule. Hypercalcemia (high blood calcium level) can occur in normal persons exposed to chlortalidone but is more likely to occur when persons with sub-clinical hyperparathyroidism are exposed to chlortalidone.
Chlortalidone, also known as chlorthalidone, is a thiazide-like diuretic drug used to treat high blood pressure, swelling including that due to heart failure, liver failure, and nephrotic syndrome, diabetes insipidus, and renal tubular acidosis. Because chlortalidone is reliably effective in most patients with high blood pressure, it is considered a preferred initial treatment. It is also used to prevent calcium-based kidney stones. It is taken by mouth. Effects generally begin within three hours and last for up to three days. Chlortalidone is more effective than hydrochlorothiazide for prevention of heart attack or stroke.Common adverse effects include low blood potassium, low blood sodium, high blood sugar, dizziness, and erectile dysfunction. Other adverse effects may include gout, low blood magnesium, high blood calcium, allergic reactions, and low blood pressure. Some reviews have found chlortalidone and hydrochlorothiazide to have a similar risk of adverse effects, while other reviews have found chlortalidone to have a higher risk. While it may be used in pregnancy it is a less preferred option. How it works is not completely clear but is believed to involve increasing the amount of sodium and water lost by the kidneys.Chlortalidone was patented in 1957 and came into medical use in 1960. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. In 2019, it was the 135th most commonly prescribed medication in the United States, with more than 4 million prescriptions. Medical use
High blood pressure
Chlortalidone is considered a first-line medication for treatment high blood pressure.