A few of the drugs that Diovan HCT can potentially interact with include potassium-sparing diuretics like spironolactone and amiloride, barbiturates like phenobarbital and thiopental, and potassium supplements or salt substitutes with potassium. Diovan HCT drug interactions can change the way your body metabolizes the drugs, cause your blood pressure to decrease too much, and cause high blood sugar, among other things. Talk with your pharmacist or healthcare provider about any Diovan HCT interactions that may apply to you.