Hydrochlorothiazide (HCTZ) is a medication licensed for the treatment of high blood pressure (hypertension) and water retention (edema). This drug is sold under a number of brand names, including Esidrix®, HydroDIURIL®, Microzide®, and Oretic®. It is also available as a generic. At this time, there are no over-the-counter (OTC) hydrochlorothiazide products available on the market. Hydrochlorothiazide is a diuretic, which is commonly referred to as a “water pill.” Although some diuretics can be found OTC, most (including hydrochlorothiazide) are available by prescription only.
Diuretics work by increasing the amount of salt and water that the kidneys remove from the blood (this extra liquid is passed out through the urine). This action causes a decrease in blood volume. Because of this effect, hydrochlorothiazide can lower blood pressure and help with water retention.