Key takeaways:
Diuretics are often called water pills because they help you get rid of extra fluids from your body.
There are many different types of diuretics like thiazide, loop, and potassium-sparing diuretics.
Your provider will consider other health conditions you might have as well as your background when deciding which diuretic is best for you.
Water pills, or diuretics, are some of the most commonly used medications. In fact, in 2019, two different water pills were among the top 20 medications prescribed in the U.S.
But what exactly are these water pills? And when do people take them? Well, that depends on each case, as there’s more than one type of water pill out there. There’s even over-the-counter (OTC) water pills available.
Read on to learn about water pills — what they are, how they work, and the different types available.
What are water pills (diuretics)?
First off, water pills aren't made of water. They also don’t make you more hydrated. They’re commonly called “water pills” because of how they work in the body.
You see, there’s a class of medications, called diuretics, that work in the kidneys. They help you remove excess fluid from the body through urination. In other words, diuretics are pills that help you get rid of extra water — hence the name “water pills.”
What do water pills do?
Did you know your kidneys filter more than 200 liters of blood per day? That's a lot of work! What your kidneys are doing is helping keep your body balanced by getting rid of waste and extra fluids, among other things. This is turned into urine, passed to the bladder, and then removed from the body by urinating.
What we’ve found is that we can actually change how the kidneys filter certain substances. Diuretics usually make you filter out more fluid. But each type of water pill does this in a different way.
By removing extra fluid, diuretics can help manage different medical conditions, like high blood pressure, heart failure, and swelling from fluid buildup (edema). As such, many people take diuretics for these health conditions.
Types of water pills
There are many diuretics available for people to take. Most have been on the U.S. market for several decades and have generic versions available. So regardless of which one your healthcare provider suggests for you, they’re generally inexpensive.
Diuretics can be broken into different classes based on how they work in the kidney. Depending on how they work, this can make them a more preferred treatment option for certain conditions. Some diuretics make you lose more water than others, and side effects can vary between classes.
Let's take a look at the most common diuretic classes. Keep in mind this list isn’t all-inclusive. There are other, less prescribed water pills used in certain situations.
Thiazide and thiazide-like diuretics
Thiazide and thiazide-like diuretics are some of the most commonly used diuretics. They’re first-choice water pills for hypertension (high blood pressure). At higher doses, they can also help treat edema. Because they work in the kidneys, you’ll need blood tests to make sure these water pills aren’t hurting them.
Common thiazide and thiazide-like diuretics include hydrochlorothiazide and chlorthalidone. Hydrochlorothiazide is commonly added to other blood pressure medications to help boost their effects. If you see the letters “HCTZ” on your prescription label, it means hydrochlorothiazide is in the medication.
Loop diuretics
Loop diuretics are another common class of diuretics. They get rid of the most fluid of all the available water pills. They’re a preferred option for relieving edema, especially for people with heart failure.
However, one of the biggest issues is that loop diuretics can remove electrolytes, like potassium and sodium, from your blood. This can lead to dehydration, low potassium levels, and low sodium levels. Loop diuretics can also be tough on the kidneys. So you'll need regular blood tests to make sure everything is OK while taking a loop diuretic.
Some common loop diuretics include furosemide (Lasix), torsemide, and bumetanide (Bumex).
Potassium-sparing diuretics
Potassium-sparing diuretics are water pills that get rid of extra fluid. But they don’t cause your potassium levels to drop, unlike thiazide, thiazide-like, and loop diuretics.
Because these medications affect how your body gets rid of potassium, they can cause potassium levels to get too high. This is called hyperkalemia, and it can become serious. You’ll need blood tests regularly to make sure this isn’t happening to you.
Potassium-sparing diuretics include two different types of medications: aldosterone antagonists and epithelial sodium channel blockers.
Aldosterone antagonists
Aldosterone antagonists include spironolactone (Aldactone) and eplerenone (Inspra). These medications work by blocking a hormone called aldosterone in the body. Aldosterone causes the body to hold on to more sodium (and fluid) but get rid of potassium. By blocking aldosterone, these water pills stop your body from holding on to extra fluid.
Aldosterone antagonists aren't really good at lowering blood pressure or swelling on their own. But they can be helpful as add-on medications when other treatments aren’t working well enough. Spironolactone can also be used off-label to treat non-heart conditions, such as acne.
Epithelial sodium channel blockers
The other group is epithelial sodium channel blockers. They’re often just referred to with the more broad term potassium-sparing diuretics. This class includes triamterene (Dyrenium) and amiloride (Midamor).
These water pills work by blocking small openings in the kidneys where sodium is absorbed. The more sodium the kidneys absorb, the more fluid the body holds onto. By blocking these openings, these water pills stop the body from hanging on to extra water.
Epithelial sodium channel blockers don’t lower blood pressure or relieve swelling much on their own either. But they can be used instead of a potassium supplement to help raise potassium levels.
What water pills are available over the counter?
There are several products available OTC that cause a diuretic effect. Most of these use either caffeine or pamabrom as the key ingredient. Both of these water pills stimulate the kidneys to make urine faster than usual. They’re intended to help with bloating or slight swelling, usually due to menstrual cramps. They shouldn’t be used as a replacement for prescription diuretics. They also shouldn’t be combined with prescription diuretics unless a healthcare provider has told you to do so.
Which water pill is best for you often comes down to your medical history. As discussed above, some of these medications work better to lower your blood pressure or treat heart failure.
Other health problems you may have or medications you’re taking may limit which diuretic you can take. For instance, if you have a history of gout, your healthcare provider may avoid prescribing you diuretics to help prevent a gout attack. Another consideration is how well your kidneys work since these medications work in the kidneys.
If you’ve been prescribed a diuretic, be sure to ask your healthcare provider why they chose it for you. They can help you understand why that water pill is the best one for you.
The bottom line
Water pills can play a main role in treating some common conditions, like high blood pressure. They mainly work by getting rid of extra fluid in your body through your kidneys. But because they work in the kidneys, you’ll need blood tests to make sure they’re not causing you to lose too much fluid or electrolytes. Which water pill is best for you will depend on what health conditions you have and what your provider may think is the right fit for you.
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