High Blood Pressure, Diuretics, And Frequent Urination: Will You Need To Pee All The Time?

When your doctor first notices that you have high blood pressure, they will likely recommend that you take a good look at your lifestyle. If your diet could be healthier, you'll be asked to take steps to get there. If you haven't been exercising, you'll be advised to start. If you smoke, you'll sternly be told to quit — yesterday, if possible. 

Your doctor will want you to come in multiple times to check if your blood pressure changes over time, and may well advise you to monitor your blood pressure at home as well. If it consistently stays high — 140/90 or over — despite a healthy lifestyle, you are very likely to end up with a prescription for at least one medication to lower your blood pressure. 

So, if you are newly considered a candidate for hypertension medications, there's a very good chance that your doctor will first prescribe you one of many diuretics, most commonly a sub-class called thiazide diuretics. These reduce your blood pressure by removing excess fluid from your blood stream, and also relax the blood vessels.

You'll probably have heard about diuretics before you start taking them. More specifically, you'll likely know them by their colloquial name, "water pills". Given that moniker, nobody can blame you if your first question about taking diuretics is: "Will I need to pee all the time?"

How do diuretics work?

Diuretics reduce blood pressure by eliminating excess fluids and sodium (but also chloride, usually potassium and magnesium) from your body.

The electrolyte sodium (salt) can pose quite a challenge, given that it attracts water like crazy. If you suffer from high blood pressure, that extra water, which translates to a higher blood volume, keeps your blood pressure high. Diuretics work, to put it simply, by preventing the kidneys from reabsorbing sodium, in turn allowing it to leave your body — by way of urination, and of course together with excess fluid. This is why they're known as water pills.

So, will you need to pee all the time once you start taking diuretics for your hypertension?

Will you constantly be looking around for a rest room, wherever you go and every five minutes? When I was first prescribed a diuretic for my hypertension — a low dose of hydrochlorothiazide, one of the most common thiazide diuretics around — that was exactly my question. I even remember someone telling me, "well, duh, that's what they're for!" when I wondered this. 

The truth about taking diuretics for high blood pressure is both more complex and more manageable. 

Here are some things you need to know about frequent urination when you're taking diuretics:

• The extent to which your urine output will change after you start taking diuretics depends on the kind of diuretic and the dose. A lower oral dose of a thiazide diuretic or a potassium-sparing diuretic will not cause changes as noticeable as a higher dose of loop diuretics, which may be administered via an IV in a hospital if your blood pressure rises to genuinely dangerous levels. 
• Diuretics are fairly fast acting, so your timing matters. For that reason, your doctor, your pharmacist, or both, should tell you to take your diuretic in the morning, so that you do not find yourself waking up because you need to urinate. If you have especially busy morning schedules, you could discuss taking your diuretics in the late morning or early afternoon to avoid increased urinary output during an awkward time. 
• You may find yourself feeling rather thirsty when you start taking diuretics. Increased fluid intake will further increase your need to pee. On the more dangerous side, elderly women in particular are also at risk of hyponatremia — abnormally low sodium levels, which can cause fatigue, nausea, headaches, weakness, and irritability, among other symptoms — when they take diuretics. For this reason, they will often be advised to limit their fluid intake. 
• People who first start taking diuretics may be keenly aware of the potential changes these medications can cause in their urination patterns. There's the risk that you'll experience something like a placebo effect, in which you feel like you need to pee more because that is what you are expecting. You may also observe actual changes in your urination output. Over time, as you get used to your new diuretic, it should not have a noticeable impact on your need to go to the bathroom any longer. On the other hand, your diuretic prescription will hopefully serve you well in lowering your blood pressure!

Before I was asked to write this piece, I hadn't consciously considered how taking diuretics impacts my need to go to the bathroom in a long time — because I really don't notice. Having said that, I do take a low dose of a medium-potency diuretic, and the ultimate answer will be different for everyone.