Hydrochlorothiazide is a medication used to treat high blood pressure and fluid retention. It is a type of thiazide diuretic that helps the body to get rid of excess salt and water. There are a few synonyms for hydrochlorothiazide, including HCTZ, HydroDIURIL, Microzide, and Esidrix. These synonyms are simply different brand names for the same medication. When prescribed by a doctor, hydrochlorothiazide is given in specific dosages and monitored carefully to ensure proper treatment. It is important to always follow your doctor's instructions and not deviate from your prescribed dosage as hydrochlorothiazide can interact negatively with other medications or have unwanted side effects.