What are Diuretics, Know its Functions, Uses, Types, Side Effects, Contraindications, Effects on Body

What are Diuretics & What Is Their Function?

A diuretic is any substance that promotes the production of urine. Diuretics are water pills and are mainly used for improper blood pressure patients. These pills prevent water retention in the body and help to get rid of them through urination.

All the fluid that is accumulated in the body needs to be controlled. This control is primarily done by the kidneys and this balance is maintained by the kidneys by maintaining the proportion of sodium and chlorides in the body. The amount of sodium, chlorides and water are carefully balanced in a body and it is maintained by a delicate ratio that is important for the body. If the chlorides along with the sodium are eliminated by the body, water is also expelled. If the sodium and chlorides are retained by the body, then the water also remains. The way that the sodium, chlorides and the water is eliminated is kind of a complicated process. The kidney tubules filter out these components from the blood and other small molecules are also filtered and these are then employed in the formation of urine. Most of the water, however, is also reabsorbed into the body before they are eliminated in the form of urine. The process is extra complex because there are various processes that are active throughout the filtration and reabsorption of the sodium, chlorides and water in and off the body, which finally leads to the expulsion of the extra fluids in the form of urine.

What are Diuretics & What Is Their Function?

Diuretics are involved in this process as they increase the amount of fluid expelled in the form of urine. The diuretics make sure that the majority of sodium and chlorides are expelled out of the body. When the sodium and chlorides leave the body, they extract with them a major proportion of water from the body. Since the amount of sodium and chlorides in the body has an important effect in determining the amount of water in the body, the diuretics function by maintaining the total-body sodium and chlorides content.

Why Are Diuretics So Important?

There remains a delicate balance between the amount of sodium that we intake through our food to the amount of sodium expelled by the body. If this balance is somehow disrupted, it causes great complications related to the amount of water left in the body. It causes certain physiological hazards such as edema, pulmonary edema and also high blood pressure. If again the amount of sodium that is removed from the body is abnormally high, it leads to a higher removal of water from the body and this may lead to renal failure. Diuretics are hence used when the body cannot in itself maintain this delicate balance between the amounts of sodium taken in by the body to the amount of sodium lost by the body.

Are Diuretics Used Alone? In Which Cases Are Diuretics Used?

Diuretics are used in association with many other medications, in the treatment of edema related to congestive heart failure, corticosteroids or even in the case of estrogen therapy. Diuretics are also used in case if edema that is associated with renal failure of nephrotic syndrome and in the treatment of chronic renal failure. Diuretics may be used in the treatment of urinary calcium excretion and in prevention of kidney stones. Diuretics are also used therapeutically for hypertension. Hence, diuretics are of diverse use and treat a variety of problems.

What are the Types of Diuretics?

The most important difference that exists among different types of Diuretics is mainly in their potency. The potency of diuretics is a factor that is mainly dependent on the site at which the diuretics act in the renal tubules. The following are the different types of diuretics:

Thiazide Diuretics: These are the most common and well known diuretics. These diuretics act by decreasing the fluid in the body and also relaxing the blood vessels. Thiazide Diuretics are also used for treating high blood pressure. Thiazide Diuretics are taken in association with other medications that are used to lower the blood pressure. The common thiazide diuretics used are: chlorothiazide, chlorthalidone, hydrochlorothiazide, metolazone and indapamide.

Loop Diuretics: Loop diuretics are one of the most potent of all diuretics. Diuretics mostly increase the elimination of sodium and chlorides primarily by preventing the reabsorption of sodium and chlorides. The high potency of loop diuretics is basically because of the unique site if it’s action which is the loop of Henle. Some of the common loop diuretics include: torsemide, furosemide, bumetanide and ethacrynic acid.

Potassium Sparing Diuretics: The potassium sparing diuretics reduce the amount of fluid in the body without your body losing potassium, which is a very important nutrient in the body. The other diuretics usually cause a lot of potassium loss, which can, in the long run cause bodily complications like arrhythmia. Potassium sparing diuretics are generally prescribed to those individuals who are at a risk of low potassium levels or who take such medications that otherwise lower the amount of potassium in the body. Potassium Sparing Diuretics, however, are not as effective in reducing the blood pressure levels as the other diuretics do. Potassium Sparing Diuretics are usually prescribed along with another medicine that reduces blood pressure. Some of the commonly used potassium sparing diuretics include medicines like: amiloride, spironolactone, triamterene and eplerenone.

Carbonic Anhydrase Inhibitors: Carbonic anhydrase inhibitors increase the excretion of sodium, potassium, bicarbonate and water from the renal tubes from the kidney.

Osmotic Diuretics: Osmotic Diuretics are required for the filtration of substances that have low molecular weight. These substances are filtered from the renal tubules, which are present in high concentration in the blood. Osmotic diuretics prevent the re-absorption of water, chlorides and sodium.

What are the Side Effects of Diuretics?

When the diuretics are taken according to the prescribed amount, they are well tolerated. However, diuretics may still cause some side effects. Some of the common side effects of diuretics are:

  • Potassium levels that are too low for normal blood.
  • Potassium levels that are too high for normal blood.
  • Low levels of sodium.
  • Headache.
  • Thirst.
  • Dizziness.
  • Increased blood sugar level.
  • Muscle cramps.
  • Increased cholesterol levels.
  • Rashes on the skin.
  • Gout.
  • Diarrhea.
  • Dry mouth.
  • Weakness and fatigue.
  • Lethargy.
  • Drowsiness.
  • Confusion and lack of judgement.
  • Seizures and epilepsy.
  • Hypotension.
  • Decreased production of urine, which is called oliguria.
  • Tachycardia.
  • Gastrointestinal disturbances that might also occur.

More Serious Side Effects Of Diuretics Are:

The more serious side effects of taking Diuretics may be the following: Allergies, kidney failure or renal failure, irregular heartbeat and palpitation. If the side effects of the diuretics are too hazardous so much so that they make your life troublesome, then you should contact your doctor. The doctor might prescribe you some other medications or give the diuretics in association with other medications that might prevent such side effects. You should, by no means stop taking the diuretics, even if you face the side effects, before consulting your doctor about the course of action you should take.

What are the Common Drugs that Interact with Diuretics?

Diabetes Medication & Diuretics: If the thiazide diuretics are taken in association with oral anti-diabetic drugs, then it may cause a decreased blood level of the anti-diabetic drug. In this case, the dosage of the antidiabetic drug has to be increased.

For the patients who take digoxin, the low level of potassium that is caused by the concurrent action of digoxin and the diuretics like thiazide or other loop diuretics may cause irregular heartbeat and general weakness in the body.

Lithium& Diuretics: If lithium medicines are consumed along with diuretics, then this may induce lithium toxicity, as the level of lithium removed by the kidney is reduced considerably. Lithium levels in the body have to be administered systemically.

ACE Inhibitors & Diuretics: If the potassium sparing diuretics are given along with angiotensin converting enzyme or ACE inhibitors, they escalate the levels of potassium greatly. Severe hyperkalemia or elevated levels of potassium may cause weakness in muscles, slow heart rate and tiredness in the body.

Anti-Hypertensive Medications & Diuretics: Diuretics are generally administered with other medications that control high blood pressure and heart diseases. This, however, may cause electrolyte level anomalies, like a reduced level of potassium in the body.

Diuretics are generally safe to take, but as already mentioned, they at times may cause severe as well as minor side effects. These have to be dealt effectively. Also, diuretics along with other medications may cause some severe interactions that might be harmful for the body. If your body is dealing with other potentially harmful or detrimental condition, this might also influence the diuretics when taken during these conditions.

Side Effects Of Diuretics According To The Type Of Diuretics

There can be 3 types of diuretics which have different side effects pertaining to each of them.

Side Effects of Thiazide Diuretics: Azotemia, hyponatremia, hyperglycemia, hyperlipidemia, dehydration with increased risk of hypovolemia and hypotension, hypertriglyceridemia, hypokalemia, hyperuricemia (at low doses), hypercholesterolemia and metabolic acidosis.

Side Effects of Loop Diuretics: Azotemia, dehydration with risk of hypovolemia and hypotension, dose-related ototoxicity, hyperuricemia, metabolic alkalosis, hypokalemia, hypomagnesaemia and hyponatremia.

Side Effects of Potassium Sparing Diuretics: Gastric problems, metabolic acidosis, peptic ulcers, gynecomastia and hyperkalemia.

Pathophysiology of Side Effects of Diuretics

Sodium & Potassium Content: Overdose of diuretics imbalances the level of sodium and potassium content of the body. The body may retain too much of both or too little of either. This results in weakness of the body and makes the patient lethargic. Low potassium levels results in weak muscles. The muscle fibers start breaking and are released into the blood stream. This further damages the kidneys and may eventually cause paralysis of the body. Heart problems can also be detected like irregular heartbeat. It may also cause fatigue and constipation. On the other hand, low sodium levels in the body do show any severe symptoms; however, does affect the body. Adverse situations occur when this causes muscle spasms, nausea, irritability and fatigue. If not checked, then the person can experience fits, lightheadedness, hallucinations, confusion and may lead to stupor and coma. Various kinds of brain complications occur due low sodium levels as a side effect of diuretics.

Loss of Magnesium from Diuretics: Due to loss of magnesium, lot diseases can creep into our body. We feel depressed more often, there are persistent headache and sleep problems. People also suffer from hypertension, migraine, asthma, osteoporosis and premenstrual syndrome. Heart diseases also show themselves in the form irregular heartbeats, chest pain and coronary artery disease. Neurological problems may also arise such as, epilepsy, Parkinson’s disease etc.

Increase in Uric Acid due to the use of Diuretics: Increase in the level of uric acid generally results in increase of gout problems, that is, inflammation of joints if the uric acid crystals get deposited in the joints. Besides this, the patients may also suffer from frequent fevers, chills and fatigue. Finally, uric acid may also lead to kidney problems, such as formation of kidney stones or problems regarding urination.

Electrolyte Imbalance & Dehydration from Diuretics: Diuretics increase the urine output and thus more and more water is lost from the body causing dehydration. Dehydration causes dry mouth, a feel of increased thirst, headaches and dizziness. Due to loss of water from the body, the volume of blood also decreases, which results in drastic fall of blood pressure. Since dehydration reduces the water content of the body, the uric acid can form crystals and accumulate in the various joints of the body. We know water pills caused heightened excretion of urine, which is followed by decreased level of electrolytes in the body because diuretics increase the salt content in urine. Electrolytes are substances that impart electrical charge once dissolved in water. These help in the proper functioning of muscles, nerves and tissues. Thus, malfunctioning of these body parts are bound to occur.

Weight Loss from Diuretics: Diuretics may apparently seem to be working as weight loss agents, but these pills do not burn the extra fat or calories of our body, on the contrary the loss of weight is entirely due to loss of water from the body. This side effect of diuretics affects the heart, lungs and kidneys. Once the consumption of diuretics is stopped, the body replenishes itself with water and the weight of the person will increase.

In what Conditions are Diuretics Contraindicated? What Should You Inform Your Doctor Before Taking Diuretics?

Before you take the diabetes medication that had been prescribed to you, you should be careful that you let your doctor know about other medical conditions that might be influencing your body. The medicines that you take for other medical conditions can react with the diuretics that have been prescribed. So, you should always inform your doctor about any conditions or issues which include:

  • Diabetes.
  • Pancreatic conditions.
  • Lupus.
  • Gout.
  • Menstrual problems like irregular menstrual cycles.
  • Kidney or renal problems of any sort.
  • Frequent dehydration of the body.

Some Frequently Asked Questions About Diuretics.

Q. Do diuretics cause weight loss? Why or why not?

A. Our body needs to maintain a certain level of hydration to survive as a result through the natural inducement of thirst and greater water retention (greater extraction of fluids from food in our intestines) our weight will gyrate back to a certain level of equilibrium. Diuretics are drugs (Esidrix or Zaroxolyn) that can be used to control high blood pressure, but all drugs do come with side effects. Years ago I found a means of lowering my blood pressure without any drugs. I would cycle to work that took me about over an hour about 35 km away. I was very pleased that my blood pressure plunged to normal and it lasted the duration I was at work and the cycle back gave me the additional 8 hours as I arrived home. I have been free of any medication for the last 7 years now as long as I do intensive exercises.

Q. What Is A Diuretic & What Are Its Effects On The Body?

A. A diuretic is any substance that promotes the production of urine. This includes forced diuresis. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way. Alternatively, an antidiuretic is an agent or drug which reduces the excretion of water in urine. Based on the type of diuretic used, the adverse affects may include involvement of CNS and other bodily functions, which could be reversible or not.

Never take a diuretic, for that matter any medicine without being prescribed by a qualified medical practitioner.


In conclusion we can say that diuretics can be consumed only after a doctor has prescribed it. We should never experiment with medicine of any kind. Older people, pregnant women, or mothers who breastfeed their children should not be consume diuretics, as it can make the babies dehydrated and could hinder their bone development. Thus, a doctor’s surveillance and guidance is a must while dealing with Diuretics.

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:September 23, 2021

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