Hypertension (high blood pressure) is a risk factor for developing heart disease.1 High blood pressure narrows, tightens and blocks blood vessels. This makes it difficult for blood to flow through and puts extra strain on the heart to pump, which can cause heart failure over time. By correlation, hypertension it is one of the biggest leading causes of death worldwide.
In the past couple of decades, the number of people diagnosed with hypertension has increased. Antihypertensive medications are helping control the problem. There are many types of blood pressure-controlling medications and drugs. Diuretics are one of the most commonly used to treat hypertension. They have been an effective strategy in preventing strokes and 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 removed and eliminated from the body through urine.2 Diuretics help lower blood pressure by getting rid of extra sodium (salt) and water in the body. By lessening the amount of total fluid in the body, 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 generally mild side effects.3 Common types of diuretics for hypertension include thiazide, potassium-sparing, loop, and combination diuretics.
Thiazides are a class of diuretics that help with blood pressure, congestive heart failure, and bodily swelling caused by fluid (edema). They are of 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 tubule.4 They don’t let the kidneys take salt back up into the blood stream. The salt is instead excreted out through the urine, and with it, lots of water.
As implied by the name, 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 is really important for many functions of the body, such as 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 that may not be effective enough. For this reason, potassium-sparing diuretics can be prescribed to avoid the issue.
Like thiazides, these diuretics also work in the distal tubule of the kidney, but they don’t result in the same amount of potassium loss.7 Some medications in this class of diuretics are used for helping multiple issues at a time such as liver failure, heart failure, and high blood pressure. Potassium-sparing medications are weaker than the other kinds of diuretics, so they are rarely prescribed on their own.3
Possible side effects
Diuretics, when taken as directed by a doctor, are generally very safe. The most common side effects of diuretics are frequent urination and loss of salt. Frequent urination is usually only temporary and goes back 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 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.
- Mills, K. T., Stefanescu, A., & He, J. (2020). The global epidemiology of hypertension. Nature reviews. Nephrology, 16(4), 223–237. https://doi.org/10.1038/s41581-019-0244-2
- Krakoff, L. R. (2005). Diuretics for Hypertension. Circulation, 112(10), 127–129. https://doi.org/10.1161/circulationaha.105.570192
- Shah, S. U. (2004). Use of diuretics in cardiovascular disease: (2) hypertension. Postgraduate Medical Journal, 80(943), 271–276. https://doi.org/10.1136/pgmj.2003.010843
- 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/
- Image by Steve Buissinne from Pixabay