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Diuretics: Navigating the Waters

1 Contact Hour including 1 Advanced Pharmacology Hour
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This peer reviewed course is applicable for the following professions:
Advanced Practice Registered Nurse (APRN), Certified Nurse Midwife, Certified Nurse Practitioner, Certified Registered Nurse Anesthetist (CRNA), Clinical Nurse Specialist (CNS), Licensed Practical Nurse (LPN), Licensed Vocational Nurses (LVN), Nursing Student, Registered Nurse (RN), Registered Nurse Practitioner
This course will be updated or discontinued on or before Monday, October 27, 2025

Nationally Accredited

CEUFast, Inc. is accredited as a provider of nursing continuing professional development by the American Nurses Credentialing Center's Commission on Accreditation. ANCC Provider number #P0274.


≥92% of participants will know how to safely administer diuretics.


By the end of this course, the learner will be able to:

  1. Explain why diuretics are prescribed.
  2. List the main classes of diuretics.
  3. Delineate the mechanism of action for each class of diuretics.
  4. Differentiate the contraindications for giving a diuretic.
  5. Describe the nursing considerations when giving diuretics.
CEUFast Inc. and the course planners for this educational activity do not have any relevant financial relationship(s) to disclose with ineligible companies whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.

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Diuretics: Navigating the Waters
To earn of certificate of completion you have one of two options:
  1. Take test and pass with a score of at least 80%
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Author:    James Wittenauer (RN, MSN, MPA, RN-BC)


The administration of medications is one of the primary functions in nursing, with an ever-growing list of classes of drugs to be given. The nurse must be knowledgeable in giving these medications concerning the class of the medication, the intended effects, the side effects, lab considerations, nursing implications with the medicine, and patient teaching that always needs to accompany the giving of medications. A class of drugs given frequently today is that of diuretics. In this course, we will look at this class of medicines up close to know the basics of this class and how important they are in your patient's care.

Case Study

Imagine you are the nursing supervisor coming in to assist with a rapid response on a telemetry unit. The patient in trouble is in a stable ventricular tachycardia with a pulse but is quickly stabilized and moved to the intensive care unit. During the post-event debriefing, it was found that the patient, admitted for congestive heart failure (CHF), had a dangerously low potassium level at the beginning of the shift that was not corrected before the next dose of intravenous Lasix was administered. Could this have been prevented?

The answer to the question in this scenario is: YES.

The rapid response may have been prevented if the nurse checked the potassium levels before giving the next dose of Lasix. Why is this potassium level so important? What does Lasix have to do with the potassium level? To answer this question, we need to look at the medication class of diuretics from a nursing point-of-view.


Why are diuretics prescribed?

Diuretics are a class of medication that works by helping the body to rid itself of excess fluid (, 2018). Various disease processes cause the body to retain excess fluid. While we cannot go over all of them, the significant reasons that the patient retains excess fluid and may need a diuretic are congestive heart failure (CHF), renal impairment, and high blood pressure (, 2018).

Congestive Heart Failure (CHF)

We look at the heart as if it were a pump to pump blood to the rest of the body. In CHF, the pump is not working as effectively as it should be for a multitude of reasons. When the blood is not being pumped effectively, blood backs up in the vascular and cardiovascular systems. It causes signs and symptoms, including swelling in the lower extremities, difficulty breathing, abnormal lung sounds, coughing up frothy pink sputum, and even orthopnea, which all could require sleeping with many pillows to breathe when sleeping. The reason behind why a patient has CHF can be from a myocardial infarction (MI), atrial fibrillation, or other disease processes (, 2018). The reason for prescribing a diuretic for a patient with CHF is to reduce the amount of circulating fluid in the system so that the heart pump can function more effectively (, 2018).

Renal Impairment

Renal impairment, whether it be complete renal failure, renal insufficiency, chronic kidney disease, or acute kidney injury, results in the renal system not being able to excrete the wastes and excess water from the body. Renal impairment can result from a hypotensive episode where the organs themselves did not get enough perfusion, a complication from diabetes, or damage from high blood pressure, just to name a few. Using a diuretic in a patient with renal impairment will help rid the body of excess fluid and waste products that it cannot do on its own.


High blood pressure, or hypertension, is a condition where the vasculature force, more so the arteries, makes it more challenging to get the blood out to the rest of the body. The reasons for high blood pressure can range anywhere from genetics to lifestyle choices, and the complications from high blood pressure can include issues such as renal failure, impotence, stroke, vision damage, and heart damage (, 2018). The rationale behind using a diuretic in a patient with hypertension is to reduce the amount of circulating blood volume in the arterial pressure part of the vascular system so that the heart does not need to work so hard to pump the blood out to the rest of the body.

Types of Diuretics

There are several different types of diuretics that a provider may prescribe for a patient. The choice of diuretic prescribed will depend on the disease process behind the prescription, the patient's condition, individual lab results, outpatient care, and the insurance coverage the patient has. According to (2018), there are five major classes of diuretics used. These classes include (, 2018):

  1. Carbonic anhydrase inhibitors
  2. Loop diuretics
  3. Potassium-sparing diuretics
  4. Thiazide diuretics
  5. Osmotic diuretics

Each type of diuretic works in a different way to produce the diuretic effect on the body.

Carbonic Anhydrase Inhibitors

The first class, the carbonic anhydrase inhibitors, works by inhibiting bicarbonate in the kidney's proximal tubule, resulting in a diuretic effect.

According to Aslam and Gupta (2020), carbonic anhydrase inhibitors work to block carbonic anhydrase, which is produced in the body to convert carbonic acid to water and carbon dioxide. By blocking the action of this enzyme, the urine becomes more alkaline, and blood becomes more acidic. When this happens, the body rids itself of more urine to compensate due to the acid-base balance change.

Examples of medications in this class include (, 2021):

  • Acetazolamide
  • Dichlorphenamide
  • Methazolamide

Loop Diuretics

The next main class of diuretics is called loop diuretics. Loop diuretics work by binding the reabsorption of sodium chloride (NaCl) in the ascending Loop of Henle, which helps in the excretion of free water.

Examples of this type of diuretic include (Huxel et al., 2020):

  • Furosemide (*Most common; Trade name: Lasix)
  • Torsemide
  • Bumetanide
  • Ethacrynic acid

Potassium-Sparing Diuretics

The next class of diuretics is called potassium-sparing diuretics. As the name implies, potassium-sparing diuretics leave behind the potassium in the system. This reduces the possibility of hypokalemia or potassium deficiency for the patient. Other types of diuretics typically have the action of removing fluid as well as electrolytes. These electrolytes generally include potassium.

Examples of potassium-sparing diuretics include (Knott, 2020):

  • Amiloride
  • Triamterene
  • Eplerenone
  • Spironolactone

Thiazide Diuretics

The fourth and last primary class of diuretics is called thiazide diuretics.

According to Akbari and Khorasani-Zadeh (2020), this class of diuretics works by inhibiting the reabsorption of anywhere from three to five percent of luminal sodium in the distal convoluted tubule within the nephron, which promotes both natriuresis and a diuretic effect.

The three most common medications used in this class of drugs include (Akbari & Khorasani-Zadeh, 2020):

  • Hydrochlorothiazide
  • Chlorthalidone
  • Indapamide

Osmotic Diuresis

Although not used frequently, the osmotic diuretic Mannitol can be given intravenously to promote a decrease in intracranial pressure (ICP) following a traumatic brain injury with accompanying cerebral edema (, 2018).

According to Arumugham and Shahin (2021), Mannitol is given to rapidly decrease the intracranial pressure with the results of a reduced ICP evident within one hour. However, it is possible for a rebound in the ICP in the initial phase of therapy. Mannitol may also be used for treatment during an episode of acute renal failure to rid the body of excess waste products within the body.

Side Effects of Diuretics

In giving diuretic medications, the intended effects are usually lower blood pressure, reduction in swelling, decreased intraocular pressure in patients with glaucoma, or decreased ascites in patients with liver disease. However, there are also other things to consider when giving diuretics, just as there are when giving other medications. It is important to be aware of possible side effects that accompany these fluid-related changes. When physicians are prescribing a diuretic or any drug, they will consider the possible side effects when deciding which diuretic to prescribe.

The side effects of diuretics are dependent on the specific medication. Mandal (2019) provides side effects for carbonic anhydrase inhibitors, loop diuretics, potassium-sparing diuretics, and thiazide diuretics.

Carbonic Anhydrase Inhibitors

The main side effects of carbonic anhydrase inhibitors include (Mandal, 2019):

  • Allergic reactions
  • Hypokalemia
  • Drowsiness
  • Neurotoxicity
  • Kidney stones
  • Metabolic acidosis

Loop Diuretics

The side effects of loop diuretics include (Mandal, 2019):

  • Hypokalemia
  • Metabolic alkalosis
  • Ototoxicity
  • Increased uric acid levels
  • Decreased magnesium levels
  • Dehydration
  • Allergic reactions

Potassium-Sparing Diuretics

Potassium-sparing diuretics' side effects include that of (Mandal, 2019):

  • Erectile dysfunction
  • Metabolic acidosis
  • Hyperkalemia
  • Breast enlargement in males
  • Acute renal failure
  • Benign Prostatic Hypertrophy (BPH)

Thiazide Diuretics

Thiazide diuretics' side effects include (Mandal, 2019):

  • Hypokalemia
  • Increased uric acid levels
  • Impaired glucose tolerance
  • Increased blood lipid levels
  • Hyponatremia
  • Allergic reactions
  • Fatigue
  • Weakness in the limbs
  • Impotence in males

As noted earlier, the physician may already be aware of the possible side effects of diuretics. It is also the nurses' responsibility to be mindful of these potential side effects and report them to the physician if there are any concerns.

Nursing Considerations

There are many nursing considerations to keep in mind when giving diuretics to the patient.

These considerations include vital signs, lab considerations, and the timing of the medication.

Vital Signs

Vital signs, especially the blood pressure, need to be considered before administering the diuretic because certain diuretics may cause a drop in blood pressure, some more than others. A perfect example of this is Furosemide or Lasix. This is especially true if you must give the medication via the intravenous route. In addition, while it is not considered one of the main vital signs, it is always a good idea to evaluate the patient's intake and output. The reason to assess intake and output is to determine if and how well the diuretic works to get rid of the extra fluid.

Electrolyte Levels

The lab considerations are essential for any medication. Still, in giving a diuretic, especially Lasix, it is vital to check the patient’s electrolytes, focusing on the potassium and magnesium levels. If the patient has serum potassium less than the low normal of 3.4-3.5 and Lasix is given, the patient may become more prone to arrhythmias, such as ventricular tachycardia or ventricular fibrillation, due to the serum potassium level. If the serum potassium drops or stays below the normal limits, the nurse will have to notify the physician to order potassium replacement.

The other electrolyte to monitor is serum magnesium, which, if the levels fall less than 1.8 mg/dl, may also predispose the patient to arrhythmias (Lewis, 2020). The other lab considerations to look out for are the blood urea nitrogen or BUN and creatinine, especially the creatinine. The reason to look at the creatinine is that if the patient is getting too much diuretic, it may harm the kidneys, and the diuretic dose will have to be reduced or stopped.

Timing of Administration

The medication's timing is very important for nurses to consider. The diuretic timing first depends on how many times a patient is taking the medication. It is usually only taken once or twice daily. If given once a day, it should be given in the morning to work throughout the day.

If given twice daily, the second dose should be given early enough in the afternoon or early evening so that the patient may have a chance to sleep without waking up and making multiple trips to the bathroom.

Another aspect of timing, especially when in the hospital, is that the nurse may need to adjust times or hold the diuretic if the patient has a test or procedure done. During a procedure or test, it can be very embarrassing for a patient to have to go to the bathroom or be incontinent if unable to reach the bathroom in time, so it is a good idea to keep that in mind.

Patient Teaching

In every aspect regarding patient care, especially with medications, patient education is a must.

The patient should be educated on the medications they are taking before discharge. The instructions given should start with the first dose of the medication.

The patient will also need continued reinforcement education. The reason for ongoing education is that when patients are in the hospital, they may not remember the instruction given if it was done so in just one sitting due to the stress being in the hospital, lack of sleep, stress over their diagnosis, to name a few. The patient will need continued education. If the patient is in another setting, such as a clinic or home health, they will need additional education.

In providing education to the patient, the nurse needs to present the teaching in a format that the patient can easily understand and that is best for them. All patients do not learn the best from written instructions as some learn better from verbal instructions, others from written, and some from the video format. The nurse needs to decide which design is better suited to the patient before teaching. Patient teaching, at a minimum, should include the medication name, the dose, the intended effect of the medication, significant side effects, and any dietary restrictions that come with the medication.


Diuretics are but one class of medications that the nurse will need to have a strong foundation of knowledge in administering. The nurse must be knowledgeable regarding diuretics as the patient's life depends on it.

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Implicit Bias Statement

CEUFast, Inc. is committed to furthering diversity, equity, and inclusion (DEI). While reflecting on this course content, CEUFast, Inc. would like you to consider your individual perspective and question your own biases. Remember, implicit bias is a form of bias that impacts our practice as healthcare professionals. Implicit bias occurs when we have automatic prejudices, judgments, and/or a general attitude towards a person or a group of people based on associated stereotypes we have formed over time. These automatic thoughts occur without our conscious knowledge and without our intentional desire to discriminate. The concern with implicit bias is that this can impact our actions and decisions with our workplace leadership, colleagues, and even our patients. While it is our universal goal to treat everyone equally, our implicit biases can influence our interactions, assessments, communication, prioritization, and decision-making concerning patients, which can ultimately adversely impact health outcomes. It is important to keep this in mind in order to intentionally work to self-identify our own risk areas where our implicit biases might influence our behaviors. Together, we can cease perpetuating stereotypes and remind each other to remain mindful to help avoid reacting according to biases that are contrary to our conscious beliefs and values.


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  • Arumugham, V. & Shahin, M. (2021). Therapeutic uses of diuretic agents. StatPearls Publishing. [Internet].Visit Source.
  • Aslam, S. & Gupta, V. (2020). Carbonic anhydrase inhibitors. StatPearls Publishing. [Internet]. Visit Source.
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  • (2021). Carbonic anhydrase inhibitors. Visit Source.
  • Huxel, C., Raja, A., & Ollivierre-Lawrence, M. (2020). Loop diuretics. StatPearls Publishing. [Internet]. Visit Source.
  • Knott, L. (2020). Potassium-sparing diuretics. Visit Source.
  • Lewis, J. (2020). Hypomagnesemia. Merck Manuals Professional Edition. Visit Source.
  • Mandal, D. (2019). Diuretic side effects. News-Medical Net. Visit Source.