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How Do Diuretics Work : Best 101 Guide

How do diuretics work? Before pondering over the question, let us dig into what a diuretic is. These medications, also called “water pills,” aid your kidneys in eliminating surplus water and salt from your body through urine.

The pressure inside your blood vessels will be lower since there is less overall fluid present, similar to a garden hose that is not entirely turned on. This also facilitates your heart’s ability to pump blood. This is the basis of how diuretics work. 

You should take them first thing in the morning if you can because they cause you to urinate more frequently. Water pills might need to be taken once or twice a day at the same time every day.

Your doctor will typically start the common treatment modality with these as soon as possible for high blood pressure.

They include, for example:

Different groups of water pills exist:

  • Thiazide-like: These remove a fair amount of water. They have a long service life. It is a commonly used blood pressure medication.
  • Loop: They are more effective and very helpful in dire situations.
  • Potassium-sparing: They assist you in maintaining K+ while eliminating extra salt and water.

You can combine several diuretic medications and take them with other medicines, sometimes in the same pill.

In this post, we’ll talk about what diuretics treat and how they function. Additionally, it discusses how diuretics work, diuretic types, side effects, risks, and consequences.

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Photo by Towfiqu barbhuiya on Unsplash/Copyright 2021

7 Types of Diuretics

There are different types of diuretics that your doctor may advise. Each drug functions differently in terms of how it eliminates fluid or salt from the body. As you choose medication, your healthcare professional will take into account your unique situation, benefits, and risks and give you an understanding of the question, how do diuretics work?

While certain diuretic agents are available over-the-counter, their effects are often milder than those of prescription medications. Dandelion root is one of many herbal remedies that are used as over-the-counter diuretics. Herbal supplements aren’t as tightly controlled as pharmaceuticals and may interfere with other prescriptions. Before using a supplement, always consult your doctor.

1. Carbonic Anhydrase Inhibitors

Acetazolamide and other carbonic anhydrase inhibitors are primarily used for the treatment of glaucoma by lowering the fluid pressure inside the eye.

A carbonic anhydrase-limiting enzyme is how the medication functions. This enzyme in the tubule replenishes circulation with minerals, salt, and water. Because the drug restricts this enzyme, too much fluid leaves your body.

2. Sodium-Glucose Cotransporter 2 (SGLT2) Inhibitors

Inhibitors of the sodium-glucose cotransporter 2 (SGLT2) lessen the amount of sodium and glucose that enters your circulation again. It functions as a moderate diuretic because fewer sodium ions are reabsorbed into your circulation, which causes fluid levels to drop.

How do diuretics work in treating diabetes? Technically speaking, SGLT2 medications like canagliflozin and dapagliflozin are weak diuretics. However, because they lower circulatory glucose levels, they are primarily used for the treatment of diabetes.

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Photo by Kateryna Hliznitsova on Unsplash/Copyright 2020

3. Thiazide Diuretics

Thiazides stop the distal convoluted tubule of the nephron from reabsorbing salt and water. More water leaves the body.

Thiazide diuretics can also lower your body’s potassium levels, just like loop diuretics can.

High blood pressure is treated with thiazides as a first-line option (hypertension). A 2019 study indicated that thiazides are superior to ACE inhibitors as the first-line treatment for hypertension.

Thiazides may not perform as well when the glomerular filtration rate, an indicator of kidney function, is very low. Thiazides may occasionally be taken with loop diuretics to boost their effectiveness.

Diabetes insipidus and calcium-containing kidney stones are other conditions that thiazides are used to treat.

The most often given diuretics are thiazides. These medications induce your blood vessels to relax in addition to decreasing fluid retention.

Thiazides may occasionally be used with other drugs to lower your blood pressure. Thiazides include, for instance:

  • Chlorthalidone
  • Hydrochlorothiazide
  • Metolazone
  • Indapamide

4. Loop Diuretics

How do diuretics work in reducing the potassium content in the body? The loop of Henle, a region of your kidneys, is affected by loop diuretics. They rid your body of salt and extra water.

You may potentially lose too much potassium if you use loop diuretics. Hypokalemia can happen if the potassium loss is significant enough. Hypokalemia can induce irregular heart rhythms and, in severe situations, can potentially halt the heart.

Furosemide and other loop diuretics are used to treat hypertension (high blood pressure), pulmonary oedema (fluid in the lungs), generalised swelling, and hyperkalemia. They may be administered for hypercalcemia or excessive calcium levels as an off-label usage.

Some examples of this group of drugs include:

  • Torsemide
  • Furosemide
  • Bumetanide

5. Potassium Sparing Diuretics

Potassium-sparing diuretics function by increasing urine volume without lowering K+, as their names imply. Diuretics that spare K+ include spironolactone and amiloride.

How do diuretics work by preventing potassium loss? Potassium-sparing diuretics that don’t deplete you of K+, an essential nutrient, reduce the amount of fluid in your body and spare potassium by binding ENaCs or by the inhibition of aldosterone receptors in the body.

The other kinds of diuretics cause potassium loss, which can result in health issues like arrhythmia. People who are at risk for low potassium levels, such as those who take other drugs that deplete K+, may be administered potassium-sparing diuretics.

Diuretics that spare K+ do not treat high blood pressure as effectively as other types of diuretics. As a result, your doctor may advise taking a K+-saving diuretic together with other high-blood-pressure medications.

Aldosterone is a steroid hormone produced by the adrenal gland that is prevented from working by spironolactone. It lessens the loss of K+ while causing the kidneys to eliminate excess water and sodium.

Spironolactone is frequently used to prevent potassium loss brought on by loop and thiazide diuretics. Hyperaldosteronism may also be treated with it. The hormone aldosterone, which regulates your balance of salt and water, is produced excessively by the body in this condition.

Amiloride prevents your body from reabsorbing water. Amiloride is frequently used to prevent K+ loss brought on by other diuretics, much like spironolactone does.

A few further examples of potassium-sparing diuretics are:

  • Triamterene (Dyrenium)
  • Eplerenone (Inspra)

6. Osmotic Diuretics

How do diuretics work in treating glaucoma and increased intracranial tension? Osmotic diuretics use osmosis to draw in water. Water moves through osmosis when it is transferred from a less concentrated solution to a more concentrated one.

Osmotic diuretics allow the body to expel water by preventing it from being reabsorbed. They function to remove water and reduce swelling in the kidneys as well as the area surrounding the brain and eye. This can be used to treat both glaucoma and elevated intracranial pressure.

Osmotic diuretics are also used to stop rhabdomyolysis or chemotherapy-induced acute kidney failure (muscle breakdown).

7. Vaptans

In patients with heart failure, vaptans, such as conivaptan and tolvaptan, are used to treat diseases like low sodium levels. They function by raising the volume of water discharged as urine. The amount of sodium in the circulation rises as a result.

How Do Diuretics Work? – Mechanism of Action

How do diuretics work? To answer this question we need to understand the excretory system of our body. Nephrons in the kidneys are the site of action. The kidney’s nephron is in charge of filtering the liquids and waste that go into making urine. Your kidneys each contain one million nephrons.

Nephrons function as follows:

Blood passes into the glomerulus, a collection of microscopic arteries, as it enters the nephron.

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Photo by Robina Weermeijer on Unsplash/Copyright 2019

It is filtered by the glomerulus. It enables fluid, waste, and tiny molecules to enter the tubule. Larger molecules like proteins and blood cells stay in the vessels.

The tubule returns minerals to your circulation while removing waste. Urine is created in the tubule from waste and fluid.

Uses of Diuretics

High blood pressure is the most typical condition that diuretics are used to treat. Your blood pressure is lowered by the medications’ reduction of the fluid in your blood vessels. Your doctor may add additional blood pressure medications to your treatment regimen if diuretics are unable to sufficiently drop your blood pressure.

How do diuretics work in treating a variety of diseases? Healthcare professionals may prescribe diuretics to reduce fluid levels. These consist of :

  • Oedema: Diuretics reduce oedema, which typically affects the legs.
  • Elevated blood pressure: Thiazide diuretic is used to lower your blood pressure. This lessens your risk of having a heart attack or stroke.
  • Heart failure: Diuretics reduce pulmonary oedema and congestion. For heart failure, a loop diuretic is typically prescribed.
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Photo by Kenny Eliason on Unsplash/Copyright 2021
  • Kidney issues: Less water will be kept by you.
  • Liver issues: It will lessen the fluid buildup you’ll experience if you have cirrhosis.
  • Glaucoma. Your eye pressure will decrease as a result.

How to Use Diuretics?

Inform your doctor if you have diabetes, kidney illness, liver disease, or gout before receiving a prescription.

Observe the instructions on the package. If you just need to take one dose per day, take it in the morning with breakfast or immediately thereafter. Take your final dose of the day, if you are taking more than one, no later than 4 p.m.

The type of diuretic given as well as your condition will determine how many doses you take daily, the amount of time between doses,  how long you must take the medication and answer your questions on how diuretics work on you.

Write down your weight after you weigh yourself each day at the same time and on the same scale. If you gain 3 pounds in a day or 5 pounds in a week, see your doctor right away.

Have regular blood pressure and renal function checks while you are taking them. Your circulatory K+ and magnesium levels may fluctuate if you take diuretics.

Keep all visits with the doctor and the lab so that your response to the medication can be monitored.

Drug Interactions

Inform your doctor about any drug record, over-the-counter drugs, dietary supplements, and herbal therapies you take. Tell them about any further medical conditions or health problems you have as well.

They might want to monitor your blood pressure frequently, check the amounts of particular minerals in your circulation and urine, and assess how well your kidneys are functioning to understand how do diuretics work on your body. They’ll probably advise you to check how much salt you consume and stick to a low-sodium diet.

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Photo by Dan Gold on Unsplash/Copyright 2017

You may need to consume additional foods like bananas, sweet potatoes, spinach, and lentils or take a potassium supplement because some diuretics also remove K+ from your body. On the other hand, if you’re taking a potassium-sparing diuretic like amiloride, spironolactone, or triamterene, they could urge you to avoid potassium-rich foods, salt substitutes, low-sodium milk, and other sources of K+.

If you only need one dose per day, you might want to take your diuretic in the morning so you can go to bed without having to get up to use the restroom. You’ll be able to sleep through the night as a result.

Avoid using sleep aids and alcohol together. They might exacerbate negative consequences.

Inform your doctor and pharmacist about all of the medications you are taking to prevent a potential issue, including:

  • Herbal concoctions
  • Nonprescription medications
  • Vitamins
  • Dietary supplements

Diuretics are frequently administered alongside other medications. Contact your doctor if taking them together causes you to experience more side effects. The timings you take each one may need to be adjusted

How do diuretics work along with other medications? Inform your doctor of any of the following before receiving a prescription for a diuretic to avoid any side effects:

You might need to avoid or eat particular foods when taking some diuretics. Observe your doctor’s recommendations, which may include:

  • Limit salt intake
  • A potassium supplement or meals strong in K+, including orange juice and bananas.

Always consult your healthcare provider.

Side Effects of Diuretics

Potassium levels can drop after using thiazide and loop diuretics. If you use these kinds of diuretics, your doctor might urge you to cut back on salt and up your intake of K+-rich foods.

In contrast, potassium-sparing diuretics may result in excessive K+ levels. Cardiac arrest or other hazardous heart rhythm problems could result from this.

If you use diuretics, find out from your doctor if you should routinely have your K+ levels and kidney function assessed.

You might anticipate experiencing increasing amounts of urination, frequently for several hours following a dose, as the water that leaves your body must go somewhere. Take the second dose if you’re taking two doses a day no later than late afternoon so you can sleep through the night without having to get up to use the restroom.

Diuretics may also cause fluid loss if you aren’t getting enough water, so merely drinking more fluids might not be enough to prevent it. Call your doctor if you get a severe headache, are extremely thirsty or have a very dry mouth, your urine is a dark yellow colour, and you aren’t peeing much or experiencing constipation.

You can feel extremely weak or exhausted. As your body adjusts to the medication, these should diminish. If these symptoms persist, contact your doctor. That can indicate that you need to change your dose.

If your blood pressure has dropped too low or you’re becoming dehydrated, you can have lightheadedness or dizziness, especially when you stand up.

Your blood chemistry can change. You can have an imbalance of sodium or K+ in your body. You may feel weak, and exhausted, or develop headaches or cramps in your muscles as a result. It’s uncommon, but a dangerously low K+ level could cause your heart to beat more quickly (above 100 beats per minute) or you could begin to vomit.

How do diuretics work if you have diabetes? If you don’t already have diabetes, diuretics may make it more difficult for you to manage your circulatory sugar levels, which can eventually result in the disease. Gout may be more prone to strike you.

These negative effects could be amplified by using combo tablets or numerous medications. Ask your doctor what time of day is best for you to take each prescription to help reduce those chances.

Call your healthcare provider if you experience frequent or severe blurred vision, disorientation, headache, excessive perspiration, or restlessness.

If you have any of the following symptoms, please contact your doctor or nurse:

  • Fever, sore throat, cough, ringing in the ears, unusual bleeding or bruises, or rapid and significant weight loss.
  • A skin rash
  • Nausea, vomiting, or spasms in the muscles

Call them if you have any other unsettling symptoms.

Diuretics are typically well tolerated when taken as directed. They may nevertheless result in certain negative effects.

More Common Side Effects

Diuretics’ more frequent side effects include:

  • K+ levels in the circulation are either too low or too high (for K+-sparing diuretics)
  • Low amounts of sodium due to sodium loss
  • Headache
  • Dizziness
  • Thirst
  • Elevated sugar levels
  • Muscle cramps
  • Higher cholesterol
  • Diarrhoea
  • Gout
  • Skin rash

Serious Side Effects

Diuretics can occasionally have major adverse effects. These may consist of:

What You Can Do?

Consult your doctor if any adverse effects from taking diuretics annoy you. To lessen your negative effects, they might recommend a new drug or drug combination.

Do not discontinue taking your diuretic without first consulting your doctor, whether or not you are experiencing negative effects.

Risks of Diuretics

Although diuretics are generally safe, there are potential dangers if you also take certain medications or have other medical problems.

Who Shouldn’t Take Them?

If you have a sulfa medication allergy, some diuretics may make you sick.

Dehydration-related adverse effects like dizziness and fainting are more common in older adults. You and your doctor will need to collaborate closely.

With a few cautions, most diuretics are safe to use while nursing. Consult your doctor.

Children can take them without risk, but only at reduced dosages. Adults get similar side effects. However, K+-sparing diuretics may result in low calcium levels, which could harm the formation of bones.

Herb and Plant Diuretics

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Photo by Svitlana on Unsplash/Copyright 2020

“Natural diuretics” include several herbs and plants, including:

These medicines shouldn’t be used in place of a prescription drug. Consult your doctor if you have any questions about the medications and other possible treatments.

Diuretic Resistance

When a full dose of a diuretic is administered, diuretic resistance is defined as the inability to reduce oedema to the therapeutically desirable level. Poor compliance with medication therapy or dietary sodium restriction, pharmacokinetic problems, and compensatory increases in sodium reabsorption in nephron sites not inhibited by the diuretic are some of the causes of diuretic resistance.


  • Incorrect classification, such as lymphatic or venous oedema
  • Failure to follow the advised salt and/or fluid restriction
  • Ineffective drug renal absorption
    • Nonadherence
    • Doses that are excessively low or infrequent
    • Low absorption
  • Decrease in diuretic secretion
    • Uremic toxins impede the diuretic’s ability to enter the tubule.
    • Reduced flow to the kidneys
    • Reduction in the functional kidney mass

Key Takeaways

We have discussed a great deal on Diuretics. We have learned how Diuretics work and it’s the best to guide to it. The type, risk, side effects etc. are all discussed. Hope this article helped!



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