Hypertension (high blood pressure) is one of the leading causes of death worldwide.

Hypertension is a risk factor for developing heart disease.1

High blood pressure makes it difficult for blood to flow through vessels creating strain on the heart. The overworking heart muscle (myocardium) can cause heart failure over time.

Antihypertensive medications are helping control the high blood pressure problem.

There are many types of blood pressure-controlling medications and drugs. Diuretics are one commonly used medication to treat hypertension.

Diuretics have been an effective strategy in preventing heart disease since the 1960s.2

Diuretics for treating hypertension

Diuretics are regularly referred to as “water” pills”. They stimulate diuresis—an increase in the amount of urine being made.

During diuresis, blood is filtered through the kidneys while water and waste are eliminated from the body through urine.2 Diuretics help lower blood pressure by normalizing the levels of electrolytes like sodium (salt) and water in and around cells.

By normalizing these levels, the pressure inside the blood vessels will drop.

Eventually, it becomes easier for the heart to pump blood.

Diuretics all have the same goal of removing extra fluid from blood circulation. They achieve this by getting rid of it through urine.

Differences between medications have to do with how they work to do this, depending on how they act on different parts of the kidneys.

Diuretics are the go-to antihypertensive medications, because they work well, are cost effective, and have mild side effects (adverse effects).3

Common types of diuretics for hypertension include :

  • thiazide,
  • potassium-sparing,
  • loop,
  • and combination diuretics.

Thiazide diuretics

Thiazides are a class of diuretics that help with blood pressure, congestive heart failure, and bodily swelling caused by fluid buildup in tissues (edema).

They are the first kinds of medications to be prescribed when treating hypertension.

Thiazides have been shown to work very well when taken with a mixture of other antihypertensive medications.3

These diuretics target a specific part of the kidneys called the distal tubules preventing the reuptake of salt into the bloodstream. Instead, the salt is excreted in the urine, and with it, excess water.4

Loop diuretics

Loop diuretics interact with the part of the kidneys called the Loop of Henle.5

This type of medication prevents sodium and chloride from being absorbed back into the body. This results in the sodium and chloride being removed through urine along with water. 

This class of diuretics is usually reserved for people with poor kidney function, resistant hypertension, or heart failure.3

Potassium-sparing diuretics

Potassium is important for many functions of the body, like maintaining a healthy, steady heartbeat.6

Most diuretics cause too much potassium to be lost from the body. People taking diuretic medications will usually have to control potassium levels with their diet.

However, at times dietary modifications may not be enough. For this reason, potassium-sparing diuretics can be prescribed.

Potassium-sparing diuretics also work in the distal tubule of the kidneys, but the mechanism doesn’t result in the same level of potassium loss.7

Some medications in this class of diuretics are used for helping people with multiple health issues like:

  • liver failure,
  • heart failure,
  • and high blood pressure.

Potassium-sparing medications are weaker than other kinds of diuretics, so they are rarely prescribed on their own.3

Possible adverse effects

When taken as directed by a doctor, diuretics are generally safe with common adverse effects being frequent urination and loss of salt.

Frequent urination is typically temporary and returns to normal levels in a short amount of time.6

The loss of fluids through urine can sometimes lead to dehydration and very low blood pressure levels. Consult your doctor if you are frequently thirsty or have a dry mouth.

Monitor symptoms for constipation, headaches, light-headedness, and dizziness.

Diuretics may cause too much potassium to be lost from the body (hypokalemia) because of how they work. Common symptoms of hypokalemia are weakness, tiredness, or leg cramps.

Eating potassium-rich foods or taking supplements can help regulate potassium levels.

Diuretic medications can also affect blood sugar. In some clinical trials, high doses of diuretic therapy have raised concerns on their long-term effect on high blood insulin levels.3

If uncontrolled, it can lead to the onset of diabetes and gout. It is important to talk to your doctor about maintaining a healthy diet and discussing other medications you may be taking.

Relevant topics that may be of interest to you:


  1. Mills, K. T., Stefanescu, A., & He, J. (2020). The global epidemiology of hypertension. Nature Reviews. Nephrology16(4), 223–237. https://doi.org/10.1038/s41581-019-0244-2
  • Akbari, P., & Khorasani-Zadeh, A. (2020). Thiazide Diuretics. In StatPearls. StatPearls Publishing.
  • Huxel, C., Raja, A., & Ollivierre-Lawrence, M. D. (2020). Loop Diuretics. In StatPearls. StatPearls Publishing.
  • Harvard Health Publishing. (n.d.). Adding a diuretic to your blood pressure drug. Harvard Health. https://www.health.harvard.edu/diseases-and-conditions/adding-a-diuretic-to-your-blood-pressure-drug
  • Pellegrini, L. (2020, April 28). The Difference in Diuretics. ScriptSave WellRx. https://www.wellrx.com/news/the-difference-in-diuretics/