Chlortalidone

Chlortalidone, also known as chlorthalidone, is a thiazide-like diuretic drug used to treat high blood pressure, swelling (such as occurs in heart failure, liver failure, and nephrotic syndrome), diabetes insipidus, and renal tubular acidosis. Because chlortalidone is 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. Long-term treatment with 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 Organization's List of Essential Medicines. It is available as a generic medication. In 2021, it was the 127th most commonly prescribed medication in the United States, with more than 4 million prescriptions.