I am currently prescribed Hydrochlorothiazide and Coversyl(Perindoperil) for blood pressure control.

The HCL is something of a problem with frequent night time urination. No HCL, nightime visits stop but BP rises.My Gp. confirms this is the HCL effect and not from any other cause. Is there anything available which I could try ?
I also wonder if with all the advice to drink plenty water these days if it is appropriate to use diuretics;seems counterintuitive ?

Good evening, Russell,

Hydrochloric is a diuretic and an antihypertensive medication that works in two ways.

First, it inhibits the transport of sodium in the renal tubule, causing the excretion of sodium into the urine.  The excess sodium "pulls" (by a process called osmotic drag) water with it, causing the increased urine flow that one sees when one takes this drug.  The net effect is a mild sodium and water deficit, resulting in weight loss and a subtle drop in blood pressure.

The second effect is a more direct and prolonged effect upon the walls of arteries in the body.  This may be due the depletion of sodium in the walls, but more likely, it is due to a direct effect of the drug itself upon the vascular walls causing them to relax.  This results in a drop in the tension within the vascular walls with a consequent fall in the peripheral vascular resistance.  This causes the blood pressure to fall.  It is a more prolonged phenomenon and very distinct from the diuretic effect mentioned above. I know this more than you wanted to know, but humor me.

One of the most important aspects of treating hypertension is the adherence to a low salt diet. The reason why it is important is because it augments the sodium depletion that is caused by the administration of the diuretic, in this case, hydrochlorothiazide.  A salutary side effect  is that the diuretic effect of the drug is blunted and the excessive nocturnal visits the bathroom are minimized or prevented. Therefore, a 4 gram sodium diet should be prescribed with all antihypertensives, especially, diuretics like HCTZ.

A 4 gram sodium diet consists of avoiding foods that you can see salt on, avoiding foods from a can (soups/vegetables) or a plastic vacuum wrapper ( cheeses, luncheon meats, etc. they are all preserved with salt).  Adhere to this diet and your urine output will fall and you may well require less medication to control your blood pressure.

Second to lastly, you need only imbibe water or fluids when you are thirsty.  You do not need "plenty" of fluids if your kidneys are normal. Not only that, it is remotely possible for you to become ill from too much fluid if you are taking a diuretic.  Therefore, I recommend that you drink, only when you are thirsty and only enough to quench your thirst.

Lastly,  I would suggest that you limit your fluid ingestion during the evening hours.  Doing this with a low sodium diet should reduce or eliminate your nocturnal trips to the bathroom.

I hope this is of some use to you.  It is fairly complicated, so, fell free to follow.


Dr Faulkner  


All Answers

Answers by Expert:

Ask Experts


Newell R. Falkinburg, M.D. FACP


Any question regarding hypertension or clinical nephrology


35 years of experience in the field of nephrology & hypertension. Emeritus Professor of clinical Medicine at a major medical school and director of Nephrology & Hypertension at a university affiliated medical center.

M.D. Board certified internal medicine Board certified Nephrology & hypertension

Awards and Honors
Fellow, American College of Physicians

©2017 About.com. All rights reserved.