Cyclothiazide is 3,4-Dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide substituted at positions 3, 5 and 6 by a 2-norbornen-5-yl group, chlorine, and a sulfonamide group, respectively. A thiazide diuretic, it has been used in the management of hypertension and oedema. It has a role as a diuretic and an antihypertensive agent.