How long will it take for a diuretic to lower high blood pressure?

Time diuretic effect. In general a diuretic will lower the BP within 2 weeks if your BP is diuretic responsive. This will depend on how much salt you eat as well. I recommend trying the DASH eating plan see check list to test if your BP is diet sensitive first.Takes only 2 weeks but check with your team or consult me for more details.
Diuretic . Generally, diuretic drugs such as hydrochlorothiazide take about 2 hours to produce diuresis (increased urine production) and roughly 1-2 days to lower BP. But this number really depends on quite a few factors (such as drug, dose, etc) and is more of an average response than an absolute rule. Hope that helps!