Benzthiazide (trade names Aquatag, Dihydrex, Diucen, Edemax, Exna, Foven and others) is a thiazide diuretic used in the treatment of high blood pressure and edema. It is no longer available in the United States. As a diuretic, benzthiazide inhibits active chloride reabsorption at the early distal tubule via the Na-Cl cotransporter, resulting in an increase in the excretion of sodium, chloride, and water. The following is a list of possible side effects that may occur from all constituting ingredients of Exna Tablet: vomiting, diarrhoea, photosensitivity reactions, increased in uric acid concentrations, megaloblastic anaemia, thrombocytopenia. Exna tablet may interact with the following drugs and products: ACE inhibitors, angiotensin II receptor antagonists, potassium-sparing diuretics.