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.
Ménières disease
Chlortalidone reduces the volume and thereby reduces the pressure in the inner ear chambers; elevated endolymph pressure in the inner ear is thought to be the cause of Ménières disease or ’Endolymphatic hydrops.’ Synthesis of evidence from multiple small, low-quality studies indicates that chlortalidone or other thiazide diuretics are effective for Ménières Disease. Diabetes insipidus
Chlortalidone (or other thiazide medication) is a key component of treatment of nephrogenic diabetes insipidus. Nephrogenic diabetes insipidus occurs when the kidney is unable to produce concentrated urine because it has an inadequate response to vasopressin-dependent removal of free water from the renal tubular filtrate. By blocking sodium ion resorption in the distal convoluted tubule, chlortalidone induces an increase in excretion of sodium ion in urine (natriuresis). Giving chlortalidone while simultaneously restricting dietary sodium intake causes mild hypovolemia (low intravascular volume), which induces isotonic reabsorption of solute from the proximal renal tubule, reducing solute delivery in the renal collecting tubule and renal medullary collecting duct. This reduced delivery of solute to the collecting tubule and medullary collecting duct allows increased water resorption and higher concentration of urine, which leads to reversal of nephrogenic diabetes insipidus by a means that is independent of vasopressin. Adverse effects
Some reviews have found a similar risk as hydrochlorothiazide, while other reviews found a higher risk of side effects.