Hydrochlorothiazide (Microzide) is an inexpensive drug used to treat high blood pressure. It also reduces swelling and water retention caused by various medical conditions, such as heart, liver, or kidney disease. This drug is more popular than comparable drugs. It is available in multiple brand and generic versions. Generic hydrochlorothiazide is covered by most Medicare and insurance plans, but some pharmacy coupons or cash prices may be lower.