Hydrochlorothiazide is a diuretic (water pill). It works by blocking salt and fluid reabsorption in the kidneys, causing increased urine output (diuresis). It has also been used in treating mild high blood pressure, even though the mechanism of blood pressure lowering is not well understood.
Hydrochlorothiazide is used to treat excessive fluid accumulation and swelling (edema) of the body caused by heart failure, cirrhosis, chronic kidney failure, corticosteroid medications, and nephrotic syndrome. It is sometimes used alone or in conjunction with other blood pressure pills to treat high blood pressure. Hydrochlorothiazide can be used to treat calcium containing kidney stones by decreasing the amount of calcium excreted in the urine.
Hydrochlorothiazide is a white, or practically white, crystalline powder with a molecular weight of 297.74, which is slightly soluble in water, but freely soluble in sodium hydroxide solution. Hydrochlorothiazide is known as a thiazide diuretic. Thiazide diuretics act in the kidney to remove water from the blood into the urine, by causing an increase in the removal of salts such as potassium and sodium from the blood. This removal of salts causes water to be drawn out of the blood and into the kidneys, where it is then excreted in the urine.
Removing water from the blood decreases the volume of fluid circulating through the blood vessels. This drop in fluid volume results in a drop in the pressure of the fluid within the blood vessels, which helps to lower high blood pressure. It also decreases the effort required by the heart to pump blood around the body. There are many conditions which may lead to an accumulation of fluid in the body (oedema). Hydrochlorothiazide is commonly used in conditions such as heart failure, where the pumping mechanism of the heart is less effective. It is used to relieve the symptoms of heart failure, such as the shortness of breath seen with fluid on the lungs. Hydrochlorothiazide is also used to remove excess fluid associated with cirrhosis of the liver, kidney disease and premenstrual tension.