Lisinopril is a medication that is used to treat high blood pressure, heart failure, and to preserve kidney function in some patients who have chronic kidney disease.
Also sold under the brand names Prinivil and Zestril, this drug is an ACE inhibitor (angiotensin-converting enzyme inhibitor). This class of drugs works by reducing the constriction of blood vessels, allowing blood to flow more freely and the heart to pump more effectively.
Lisinopril is not a diuretic, but it can be prescribed in a combination pill with the diuretic Microzide (hydrochlorothiazide). This combination has been shown to be more effective at reducing blood pressure than either medication administered alone.
Read on to learn more about lisinopril and diuretics, including how they work together.
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What Are Diuretics?
Diuretics are pills that increase urine production. They’re also known as water pills, because they help remove water and salt from the body. In turn, this lowers blood pressure by reducing the volume of blood that the heart needs to pump.
Diuretics are primarily used to treat high blood pressure (hypertension), although they can also be used to prevent, treat, or improve symptoms in people who have heart failure, liver failure, tissue swelling (edema), and certain kidney disorders, such as kidney stones.
Diuretics act on a complicated set of processes in the body. There are three different types of diuretics. Basically, they work in the following ways:
- Loop diuretics decrease the reabsorption of salt and water into the blood.
- Potassium-sparing diuretics block the reabsorption of water into the blood.
- Thiazides block the reabsorption of sodium and water and also widen blood vessels. This type of diuretic is often the first drug given to treat high blood pressure.
Sometimes, a combination of different types of diuretics is used to treat high blood pressure and heart disease.
How Diuretics Lower Blood Pressure
Diuretics are very effective at lowering blood pressure. When the amount of salt and water in the body is reduced, the pressure on the walls of the arteries is diminished. This results in lower blood pressure.
Thiazides are particularly effective for lowering blood pressure because they also dilate blood vessels, which reduces the pressure that the vessels are under. A 2019 study found that thiazide diuretics alone are more effective than ACE inhibitors alone at treating high blood pressure.
Is Lisinopril a Diuretic?
Lisinopril is not a diuretic when it is prescribed alone. However, lisinopril-hydrochlorothiazide is a medication that combines the ACE inhibitor lisinopril with the thiazide diuretic hydrochlorothiazide to treat high blood pressure.
If you have high blood pressure and your doctor prescribes lisinopril, you should clarify whether it is being prescribed with the diuretic hydrochlorothiazide. Lisinopril-hydrochlorothiazide is sold under the brand names Prinzide and Zestoretic. These medications include a diuretic.
How Does Lisinopril/Hydrochlorothiazide Work?
The combination drug lisinopril-hydrochlorothiazide lowers blood pressure through multiple mechanisms, including:
- Lisinopril is acting as an ACE inhibitor. The medication blocks the production of the hormone angiotensin II, which causes blood vessels to constrict. By blocking production of that hormone, lisinopril causes blood vessels to relax, thus reducing blood pressure.
- The hydrochlorothiazide part of lisinopril-hydrochlorothiazide lowers blood pressure by reducing the amount of sodium and water in the body. This reduces the volume of blood that the heart has to pump.
- Hydochlorothiazide may also dilate blood vessels, which also helps lower blood pressure, but research into this is still ongoing.
Researchers are continuing to study the nuanced ways that ACE inhibitors and diuretics work independently and together to lower blood pressure.
Your healthcare provider might recommend starting with just lisinopril or just hydrochlorothiazide; in other cases, you might start with the combination pill.
If you have questions about your course of treatment, be sure to ask your healthcare provider to explain why they chose a particular treatment. You deserve to understand your treatment options, so don’t put off asking questions.
Lisinopril-Hydrochlorothiazide Side Effects
Since lisinopril-hydrochlorothiazide combines two medications, you might experience side effects from either drug. It’s common for people to feel light-headed after their first dose of lisinopril, so your healthcare provider might recommend taking the first dose at night. To reduce the risk of light-headedness and dizziness, get up slowly when rising from a sitting or lying position.
Besides dizziness, other common side effects of lisinopril-hydrochlorothiazide are:
- Dry cough
- Tingling or pain in the hands or feet
- Decreased libido (sex drive)
When to See a Doctor
Diuretics can cause a loss of electrolytes, which can lead to severe side effects like cramping and fatigue. If you experience any of these serious side effects, you should contact your healthcare provider or call 911 immediately:
- Swelling, particularly of the face or throat
- Difficulty breathing or swallowing
- Upset stomach, vomiting, or stomach pain
- Fever, chills, or sign of infection
- Muscle cramping or weakness; heaviness in the legs
- Dry mouth or thirst
- Yellow-tinged skin or eyes; gray skin
- Restlessness or confusion
- Decreased urination
- Light-headedness or fainting
- Persistent tingling in the hands or feet; pain in the big toe
- Chest pain or changes to your heartbeat
- Severe lack of energy
Lisinopril is an ACE inhibitor that is commonly prescribed to treat high blood pressure as well as heart failure and some cases of kidney disease. It is not a diuretic and does not have diuretic effects. However, it is commonly prescribed with a diuretic, sometimes in a combination pill.
A Word From Verywell
Both ACE inhibitors, like lisinopril, and thiazide diuretics, like hydrochlorothiazide, can effectively treat high blood pressure. Lisinopril-hydrochlorothiazide, sold under the brand names Prinzide and Zestoretic, is a medication that combines both of these drugs, and is thought to be more effective than either of them administered alone.
While lisinopril itself is not a diuretic, it is often prescribed with one. If you are on lisinopril-hydrochlorothiazide, you should be aware of the side effects of diuretics, including weakness and fatigue. If you ever have questions about your course of treatment for high blood pressure, don’t hesitate to ask your healthcare provider.
Frequently Asked Questions
- What’s the difference between diuretics and ACE inhibitors?
- Although diuretics and ACE inhibitors are both used to treat high blood pressure, they do so through different mechanisms. ACE inhibitors stop the production of a hormone that causes blood vessels to constrict. Without that hormone, the vessels relax. Diuretics work by getting rid of excess water and salt, reducing the volume of the blood.
- Why would ACE inhibitors be prescribed with diuretics?
- Some research has shown that ACE inhibitors and diuretics are more effective at reducing blood pressure when used together than either type of drug is when used alone. If you have any questions about your specific circumstance for being prescribed an ACE inhibitor with a diuretic, speak with your healthcare provider.