Hydrochlorothiazide is a diuretic medication often used to treat high blood pressure and swelling due to fluid build up. Other uses include treating diabetes insipidus and renal tubular acidosis and to decrease the risk of kidney stones in those with a high calcium level in the urine. Hydrochlorothiazide is less effective than chlortalidone for prevention of heart attack or stroke. Hydrochlorothiazide is taken by mouth and may be combined with other blood pressure medications as a single pill to increase effectiveness.Potential side effects include poor kidney function; electrolyte imbalances, including low blood potassium, and, less commonly, low blood sodium, gout, high blood sugar, and feeling lightheaded with standing. While allergies to hydrochlorothiazide are reported to occur more often in those with allergies to sulfa drugs, this association is not well supported. It may be used during pregnancy, but it is not a first-line medication in this group.It is in the thiazide medication class and acts by decreasing the kidneys ability to retain water. This initially reduces blood volume, decreasing blood return to the heart and thus cardiac output. It is believed to lower peripheral vascular resistance in the long run.Two companies, Merck and Ciba, state they discovered the medication which became commercially available in 1959. It is on the World Health Organizations List of Essential Medicines. It is available as a generic drug and is relatively affordable. In 2020, it was the eleventh most commonly prescribed medication in the United States, with more than 41 million prescriptions.
For diabetes insipidus, the effect of thiazide diuretics is presumably mediated by a hypovolemia-induced increase in proximal sodium and water reabsorption, thereby diminishing water delivery to the ADH-sensitive sites in the collecting tubules and increasing the urine osmolality.A low level of evidence, predominantly from observational studies, suggests that thiazide diuretics have a modest beneficial effect on bone mineral density and are associated with a decreased fracture risk when compared with people not taking thiazides. Thiazides decrease mineral bone loss by promoting calcium retention in the kidney, and by directly stimulating osteoblast differentiation and bone mineral formation.The combination of fixed-dose preparation such as losartan/hydrochlorothiazide has added advantages of a more potent antihypertensive effect with additional antihypertensive efficacy at the dose of 100 mg/25 mg when compared to monotherapy. Adverse effects
Hypokalemia, or low blood levels of potassium are an occasional side effect. It can be usually prevented by potassium supplements or by combining hydrochlorothiazide with a potassium-sparing diuretic
Other disturbances in the levels of serum electrolytes, including hypomagnesemia (low magnesium), hyponatremia (low sodium), and hypercalcemia (high calcium)
Hyperuricemia (high levels of uric acid in the blood). All thiazide diuretics including hydrochlorothiazide can inhibit excretion of uric acid by the kidneys, thereby increasing serum concentrations of uric acid.This may increase the incidence of gout in doses of ≥ 25 mg per day and in more susceptible patients such as male gender of <60 years old.