Quinethazone (INN, brand name Hydromox) is a thiazide-like diuretic used to treat hypertension. Common side effects include dizziness, dry mouth, nausea, and low potassium levels. Quinethazone (INN, brand name Hydromox) is a thiazide-like diuretic used to treat hypertension. Common side effects include dizziness, dry mouth, nausea, and low potassium levels.