Overview
Diuretics, also called water pills, are medications designed to increase the amount of water and salt expelled from the body as urine. There are three types of prescription diuretics. They’re often prescribed to help treat high blood pressure, but they’re used for other conditions as well.
The most common condition treated with diuretics is high blood pressure. The drugs reduce the amount of fluid in your blood vessels, and this helps lower your blood pressure.
Other conditions are also treated with diuretics. Congestive heart failure, for instance, keeps your heart from pumping blood effectively throughout your body. This leads to a buildup of fluids in your body, which is called edema. Diuretics can help reduce this fluid buildup.
The three types of diuretic medications are called thiazide, loop, and potassium-sparing diuretics. All of them make your body excrete more fluids as urine.
Thiazide diuretics
Thiazides are the most commonly prescribed diuretics. They’re most often used to treat high blood pressure. These drugs not only decrease fluids, they also cause your blood vessels to relax.
Thiazides are sometimes taken with other medications used to lower blood pressure. Examples of thiazides include:
- chlorthalidone
- hydrochlorothiazide (Microzide)
- metolazone
- indapamide
Loop diuretics
Loop diuretics are often used to treat heart failure. Examples of these drugs include:
- torsemide (Demadex)
- furosemide (Lasix)
- bumetanide
Potassium-sparing diuretics
Potassium-sparing diuretics reduce fluid levels in your body without causing you to lose potassium, an important nutrient.
The other types of diuretics cause you to lose potassium, which can lead to health problems such as arrhythmia. Potassium-sparing diuretics may be prescribed for people at risk of low potassium levels, such as those who take other medications that deplete potassium.
Potassium-sparing diuretics don’t reduce blood pressure as well as the other types of diuretics do. Therefore, your doctor may prescribe a potassium-sparing diuretic with another medication that also lowers blood pressure.
Examples of potassium-sparing diuretics include:
- amiloride
- triamterene (Dyrenium)
- spironolactone (Aldactone)
- eplerenone (Inspra)
When taken as prescribed, diuretics are generally well tolerated. However, they can still cause some side effects.
More common side effects
The more common side effects of diuretics include:
Serious side effects
In rare cases, diuretics may cause serious side effects. These can include:
- allergic reaction
- kidney failure
- irregular heartbeat
What you can do
If you have side effects that bother you while taking diuretics, talk to your doctor. They may prescribe a different medication or combination of medications to help reduce your side effects.
Whether or not you have side effects, don’t stop taking your diuretic without first talking to your doctor.
Diuretics are generally safe, but there are some risks if you have other medical conditions or take certain medications.
Conditions of concern
Before you take a prescribed diuretic, be sure to tell your doctor if you have any of the following conditions or issues:
Drug interactions
When you begin a new medication, make sure to tell your doctor about any other medications, supplements, or herbs you’re taking. Some medications that might interact with a diuretic include:
- cyclosporine (Restasis)
- antidepressants such as fluoxetine (Prozac) and venlafaxine (Effexor XR)
- lithium
- digoxin (Digox)
- other drugs for high blood pressure
Some herbs and plants are considered “natural diuretics,” including:
- hawthorn
- green and black tea
- parsley
These substances aren’t meant to be used to replace a prescription diuretic. If you have questions about diuretics and other treatment options, talk to your doctor.
Prescription diuretics can be helpful in treating serious conditions, such as heart failure, to less-pressing conditions, such as mild high blood pressure.
If your doctor prescribes a diuretic, feel free to ask them any questions you may have. Consider discussing these questions:
- How will I know my diuretic is working the way it’s supposed to work?
- Am I taking any medications that might interact with a diuretic?
- Should I follow a low-salt diet while taking a diuretic?
- Should I have my blood pressure and kidney function tested while taking this drug?
- Should I take a potassium supplement or avoid foods that contain potassium?
Water pills—they sound relatively harmless, no? After all, water is generally associated with all things good: glowing skin, a speedy metabolism, and the ultimate hangover cure. Yet here’s an interesting tidbit: If not taken appropriately, water pills (known as loop diuretics in the medical community) can actually be pretty dangerous, and should only be taken under a doctor's supervision. Why? Because prescription water pills are for people with high blood pressure or patients recovering from heart failure. Yet they’re more casually known as an expedited way to try to shed pounds and/or water weight—by people with perfectly pumping hearts.
The term “water pill,” in fact, has nothing to do with the scientific composition of the medication and everything to do with their prescribed purpose: to relieve fluid retention. As we know all too well, one doesn’t have to be recovering from a heart attack to retain some extra water.
So it’s easy to see where things could become, shall we say, murky. Though valid when needed for legitimate health concerns, over the counter water pills tout some understandably tempting claims. But are water pills a safe solution in the fight against bloat? We tapped a couple of experts—Neeru Bakshi, MD, and Tara Condell—to get their medical stance on the topic. The general consensus: If you are looking into water pills, be sure to only take them under a doctor's supervision.
Ahead, learn everything you need to know about water pills, including how they work and the difference between prescription and over-the-counter diuretics.
Essentially, Bakshi tells us, “Water pills—also known as diuretics—are a class of medication used to help the kidneys decrease the amount of water in the body." Typically, she adds, they’re prescribed to a patient by a medical professional to help with high blood pressure, heart failure, and edema. “If taken at the prescribed dosage, they can be very useful for people who actually need to take them,” she says. Some people have likened water pills as a solution to migraines, but there's little evidence to back this up, and experts agree you should only take them as directed by your physician.
Water pills "work by having the kidneys remove sodium from the body, and the water then follows the sodium," says Bakshi. This decrease in fluids running through your veins and arteries is what gives water pills their "anti-bloating" properties. When it comes to your natural fluid intake while on diuretics, it's best to listen to the instruction of your doctor—especially if you have kidney or heart issues—as this depends on your individual calorie intake and weight.
From a nutritional standpoint, Condell notes that diuretics are useful for a variety of medical conditions—even for treating acne—but should always be used under the care of a physician. Typically, water pills are taken orally once a day, and you may notice more urine passing within the first two weeks of use.
When it comes to water pills, there are common side effects and then there are more serious ones, especially when they're not being taken under the care of a doctor. Nasty side effects include but aren't limited to "excessive urination, dehydration, constipation, dizziness, low blood pressure, muscle cramping, and elevated heart rate,” in addition to potential interactions with other medications. Which is why, Bakshi says, you should really only take these types of pills while monitored by your physician.
It’s important to note, however, that when taken as prescribed, diuretics can be safe. Side effects are still a possibility, but if taken under the care of a medical professional, these symptoms can be dealt with in a prompt and safe manner.
There's an important differentiation when it comes to water pills: diuretics that are prescribed and diuretics that are sold over-the-counter. Considering that water pills are often taken as a weight-loss solution, it's important to get information from both a medical and nutritional standpoint.
This is important. Unlike prescribed diuretics, over-the-counter water pills are not regulated by the FDA. In other words, “The ingredients listed on the box may not actually be what is in the pill you are taking,” says Bakshi. She continues, “There is also no guarantee of the concentration of the ingredients or promise that the listed benefits of the drug are what you should achieve.” (In other words, a functioning, healthy human shouldn’t need to take water pills in the first place).
Which left us wondering, how are water pills even allowed to be sold over the counter? According to Bakshi, oftentimes, certain once-prescribed medications can be sold over the counter once deemed safe to do so. "This is the case for diuretics and other medications, like ones for heartburn. That being said, when a medication is able to be sold over the counter, it can lose the oversight by the FDA (as noted earlier) and thereby, not need to follow the same regulations as prescribed medication for safety.” She adds: “Just because a medication is available over the counter does not mean that it is safe for all people to take.”
According to our nutritional expert, Condell, “[water pills] should not be a method for tackling weight loss.” And again, she adds that they should be used under the care of a physician. (Do we sound like a broken record yet?). Bakshi, backs her up, explaining that historically, diuretics have been a medication that people use to try to lose weight, though it's not an effective strategy, and if anything, they might cause you to gain weight.
“Diuretics do not help in weight loss but can temporarily decrease someone’s weight on the scale as they are losing water. As a response to this, the body may try to retain more water, causing swelling and an increase in weight as measured on a scale. In turn, the person may think that they need to take even more diuretics, leading them down a dangerous path.”
In short, it’s imperative to talk to a medical professional before taking water pills or any other type of diuretic. Be wary of over-the-counter options, and don't treat them as a quick de-bloating trick, which can result in dangerous side effects. To best determine if water pills are right for your health needs, speak to your personal physician.