Our bodies are mostly made up of water, and we need lots of it for everything to function smoothly.
If you end up retaining too much water, though, you can get a condition called edema.
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To counteract water retention, you can take a type of medication called diuretics, but these come with risks.
Here, learn about the side effects of diuretics and what else you should know about water pills.
What Are Diuretics?
Water pills, also known as diuretics, are commonly prescribed medications. They work by affecting the way the kidneys filter blood.
Some of them block the ability of the kidneys to reabsorb sodium and/or potassium, which also pulls extra water into the urine, called potassium-sparing or loop diuretics. Others increase the rate at which urine flows through the kidneys, also known as thiazide diuretics, per the Cleveland Clinic.
Some common types and brands of water pills include the following, per the Mayo Clinic:
There are over-the-counter diuretics, like the brand Diurex (which uses caffeine as a main ingredient), but it's not typically advised to try water pills unless they've been approved by your doctor.
How Do Water Pills Work?
Regardless of the type of diuretic, all water pills increase the amount of water lost through the urine and often are used to treat a variety of conditions.
Because they eliminate water from the body, they may also cause short-term weight loss (i.e., water weight loss).
How Much Water Should You Drink While Taking Water Pills?
Exactly how much water you should drink with water pills depends on your body size, health status and whether you're taking other medications. Talk to your doctor about your optimal fluid intake, as everyone's needs are different.
Getting your fluids right is important: You don't want to drink too much water and throw off the way your body handles salt and water, but you also don't want to get dehydrated.
Who Needs to Take Diuretic Pills?
Water retention pills are often prescribed to people with high blood pressure. If diuretics alone are not enough to lower your blood pressure, your doctor may prescribe them in addition to blood pressure medication, per the Mayo Clinic.
Other conditions that might benefit from the use of diuretics include:
- Heart failure
- Liver failure
- Tissue swelling (edema)
- Certain kidney disorders (like kidney stones)
Diuretics Side Effects
Some common, less serious side effects that can occur with taking diuretics include the following, per the Cleveland Clinic:
- Peeing more than usual
- Muscle cramps
- Heart palpitations
Some other more serious complications you should look out for include:
One of the most prominent dangers of taking diuretics is dehydration. Because these medications increase urine output, they can cause your body to become depleted of water, per the Cleveland Clinic.
Early symptoms of dehydration include increased thirst, headaches and dizziness, according to the Mayo Clinic.
Diuretics also can cause your blood pressure to become dangerously low from decreased blood volume.
Finally, dehydration can exacerbate gout, as the loss of water from the body can cause crystals of uric acid to build up in the joints, per an October 2017 study in PLOS One.
2. Electrolyte Imbalances
Electrolytes are substances within your body that have an electrical charge when dissolved in water — sodium, calcium and potassium. These substances have an important role in the function of nerves, muscles and other tissues, per Cedars Sinai.
Taking water pills can cause you to develop abnormally low concentrations of these electrolytes (especially potassium) due to the increased excretion in the urine, per Harvard Health Publishing.
One kind of diuretic, known as loop diuretics, can cause you to lose sodium through your urine. Thiazide diuretics, another type of water pill, can cause you become depleted of potassium, per the National Library of Medicine.
The loss of these electrolytes can cause muscle cramping and an irregular heartbeat, per the Cleveland Clinic.
3. Constipation, Gas and Bloating
Taking water pills without drinking enough water can cause GI upset like constipation, gas and bloating. In fact, some of hydrochlorothiazide's side effects includes stomach pain; black, tarry stools; constipation and bloating, according to the Mayo Clinic.
One way to help avoid these stomach issues while taking water pills is by making sure you are properly hydrated. Talk to your doctor about how much water you should aim to drink.
4. Potential Kidney Issues
If you're taking diuretics for long periods of time and without the supervision of a doctor, you could develop kidney issues from the dehydration you experience.
Kidney problems from water pills typically only occur if you're not drinking enough water, which can lead to kidney damage or worsening kidney conditions, per the National Kidney Foundation.
While this is not as common of an issue (especially if you're staying hydrated), it is something to be aware of and talk to your doctor about.
5. Potential Drug Interactions
According to the Mayo Clinic, there are several classes of drugs that could potentially negatively interact with the diuretic hydrochlorothiazide, including NSAIDs (non-steroidal anti-inflammatory drugs), narcotic painkillers, methotrexate for arthritis and some psychiatric drugs.
Talk to your doctor about any medications you are currently taking to make sure water pills are right for you.
There are also some foods and supplements you may need to avoid taking while on water pills. You may need to follow a low-sodium or low-potassium diet, depending on the type of diuretic you're taking.
Can You Lose Weight by Taking Diuretics?
Some people may think diuretics can help with long-term weight loss, but they cannot. Water pills only remove water weight from your body, which is temporary and insignificant compared to body weight from fat and muscle, per the National Health Service (NHS).
Diuretics do not cause you to burn extra calories or lose fat; the weight loss experienced is entirely water. When you stop taking the medication, your body will regain the water lost, according to HCA Virginia Physicians.
If you want to lose weight in a sustainable way, make sure you are following a balanced diet and exercising regularly.
When to See a Doctor
If you are experiencing water retention from an underlying health condition, talk to your doctor about taking a prescription diuretic to help reduce water buildup.
If you're already taking a diuretic and you experience adverse side effects like dehydration, heart palpitations, dizziness or fatigue, talk to your doctor or visit the nearest hospital to determine whether you can keep taking them.
1. Is It OK to Take a Water Pill Every Day?
It is safe to take water pills every day if that's what your doctor has prescribed. Sometimes doctors will instruct patients to take water pills once or twice per day, usually at the same time each day, according to the Cleveland Clinic.
Do not take more than the recommended amount of water pills, whether prescription or over-the-counter, as this can lead to an electrolyte imbalance and other health complications.
2. What Time of Day Should You Take Water Pills?
It's best to take diuretics in the morning or at least six hours before you go to sleep at night. This is because diuretics make you pee more frequently. By taking them during the day, you will avoid waking up to pee in the middle of the night, per the Cleveland Clinic.
There is really no time of day that's necessarily "safer" to take diuretics. The timing is more about saving yourself nighttime trips to the bathroom.
3. How Quickly Do Water Pills Work?
Diuretics typically begin working within an hour or two of taking them, per the Cleveland Clinic. You may even feel the urge to pee within 30 minutes of taking the medication, according to the NHS.
If you're taking water pills for high blood pressure or edema, it may take a few weeks to begin noticing results, per the NHS.
- Cardiovascular Pharmacology Concepts: Diuretics
- Texas Heart Institute: Water Pills
- Cleveland Clinic: Diuretics
- Mayo Clinic: "Diuretics"
- Cleveland Clinic: "Diuretics"
- Mayo Clinic: "Dehydration"
- PLOS One: "Triggers of acute attacks of gout, does age of gout onset matter? A primary care based cross-sectional study"
- Cedars Sinai: "What are Electrolytes?"
- Harvard Health Publishing: "Tips for Taking Diuretics"
- National Library of Medicine: "Loop Diuretics"
- Cleveland Clinic: "Electrolyte Imbalance"
- Mayo Clinic: "Hydrochlorothiazide"
- National Kidney Foundation: "Can Dehydration Affect Your Kidneys"
- National Health Service: "Common questions about furosemide"
- HCA Virginia Physicians: "The Truth About Water Pills and Weight Loss"
- NHS: "About furosemide"
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.