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Systematic (IUPAC) name
7-sulfonamide 1,1-dioxide
CAS number 58-93-5
ATC code C03AA03
PubChem 3639
Chemical data
Formula C7H8ClN3O4S2 
Mol. mass 297.742
Pharmacokinetic data
Bioavailability Variably absorbed from GI tract
Metabolism  ?
Half life 5.6-14.8 hours
Excretion Primarily excreted unchanged in urine
Therapeutic considerations
Pregnancy cat.

B (D if used to treat pregnancy-induced hypertension)

Legal status

Prescription only

Routes Oral (capsules, tablets, oral solution)

Hydrochlorothiazide, sometimes abbreviated HCT, HCTZ, or HZT is a popular diuretic drug that acts by inhibiting the kidneys' ability to retain water. This reduces the volume of the blood, decreasing blood return to the heart and thus cardiac output and, by other mechanisms, is believed to lower peripheral vascular resistance. Hydrochlorothiazide is sold both as a generic drug and under a large number of brand names, including: Apo-Hydro, Aquazide H, Dichlotride, Hydrodiuril, HydroSaluric, Microzide, Oretic.


Hydrochlorothiazide belongs to the thiazide class of diuretics, acting on the kidneys to reduce sodium (Na) reabsorption in the distal convoluted tubule. This reduces the osmotic pressure in the kidneys, causing less water to be reabsorbed by the collecting ducts. This leads to increased urinary output.


HCT is often used in the treatment of hypertension, congestive heart failure, symptomatic edema and the prevention of kidney stones. It is effective for nephrogenic diabetes insipidus (paradoxical effect, which decreases urine formation) and is also sometimes used for hypercalciuria and Dent's Disease.

Hypokalemia, an occasional side-effect, can be usually prevented by potassium supplements or combining hydrochlorothiazide with a potassium-sparing diuretic.

Side effects

NOTE: This list needs references. The NIH link provided below does not agree with several items on this list.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hydrochlorothiazide". A list of authors is available in Wikipedia.
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