How Lisinopril Works

Lisinopril, sold under brand names Prinivil and Zestril, is an Angiotensin converting enzyme (ACE) inhibitor which is prescribed to patients with high blood pressure, hypertension, or congestive heart failure. Many patients wonder how Lisinopril works, so be sure to read on and find out!

How Lisinopril Works

Being an ACE inhibitor, Lisinopril reduces blood pressure. High blood pressure occurs when the outward pressure of blood onto the blood vessels is too high.

Lisinopril and other ACE inhibitors function by preventing Angiotensin from converting from Angiotensin 1 to Angiotensin 2. As suggested by the name, Angiotensin works make blood vessels (angio-) more tense (-tensin). Because Angiotensin 2 is the more active form, preventing this conversion by blocking the catalyzing enzyme works fairly well. When Angiotensin 2 is blocked, blood vessels relax and and blood pressure is lowered.

Side note: A low sodium diet helps maintain lower blood pressure for a couple of reasons. First, less sodium leads to less water retention, and as such lower volume and lower pressure within the vascular system. Second, sodium stimulates the action of Angiotensin 2, so limiting sodium intake can help lower blood pressure from two angles.

Because Lisinopril reduces the effects of Angiotensin, the follow effects are seen in patients who take Lisinopril:

  • The muscle tissue in and around the vascular system relaxes, allow for more space for bloodflow and less outward pressure being exerted from the blood onto the blood vessels themselves.
  • Kidney function changes, causing less re-uptake of water and reducing the total volume of blood in the body.

With the same capacity in the vascular system, but a lower volume of fluid flowing through it, blood pressure is lowered when fluid re-uptake is reduced. Pair this with the relaxation of the blood vessels, and Lisinopril makes for a potent blood pressure reducing agent.

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Lisinopril Side Effects

Because ACE inhibitors have a variety of actions within the body, there are a number of potential side effects which can come of taking Lisinopril.

Lisinopril Side Effects – Low blood pressure (hypotension)

Considering the sole goal of taking Lisinopril is to lower blood pressure, it might be obvious that low blood pressure would be an effect of Lisinopril. Because this is how Lisinopril works, patients need to monitory their blood pressure to ensure it does no go too low.

Common signs that you are experiencing hypotension include, but are not limited to: dizziness, vertigo, inability to attain an erection, feeling faint, light-headedness when standing up, etc.

Lisinopril Side Effects – High Levels of Potassium


Lisinopril  plays a big role in sodium-potassium pump systems, and can lead to high levels of potassium in the body. If left unchecked, this can cause issues related to fatigue, weakness, muscular pain, and other related symptoms.

Cautions related to how Lisinopril works

There are certain issues which you must look out for in the event that you are taking or are going to take Lisinopril.

  • Angioedema
  • Kidney Stress
  • Sudden cessation of taking Lisinopril
  • High doses in the case of a severe hypertensive crisis


Because of how Lisinopril works, there is a risk of angioedema and kidney stress, as well as some risks related to suddenly stopping your medication. Angioedema is the swelling of deep layers of tissue, particularly affecting the face and lips, Leaking in blood vessels in these tissues leads to intense swelling, which can be dangerous and life threatening if left unattended. Because ACE-Inhibitor related angioedema tends to affect people above the neck, risks related to swelling of the throat are of a major concern. Beyond that, excessive swelling can damage tissues, leading to long term issues such as disfigurement of the related tissues.

Kidney Stress

Another concern related to how Lisinoril works is the risk of kidney stress, also known as renal impairment. Because Lisinopril can reduce fluid volumes in the body, there may be less water flowing through the kidneys, inhibiting their ability to function. Still, some studies have shown that Lisinopril can actually help kidney function. Kidney function is of more concern when someone takes Lisinopril with a diuretic, such as risks of Lasix.

Sudden Stop in Taking Lisinopril

Third, how Lisinopril works makes it so that patients should not suddenly stop taking Lisinopril. When someone abruptly stops taking Lisinopril, they can be exposed to rebound hypertension, a condition characterized by hypertension which is acutely worse than the patient had prior to taking their blood pressure medication. Because ACE inhibitors block the action of an enzyme, stopping the medication can lead to a sudden rush of angiotensin conversion, which ultimately leads to very high blood pressure.

High dose in response to severe hypertensive crisis

Lastly, patients who experience a severe hypertensive crisis should not take a large dose of any blood pressure medication. Cranial blood pressure is regulated slightly differently than the rest of the body, and any large change in blood pressure needs to be managed with consideration that large changes in cranial blood pressure can be dangerous:

“Rapid reduction in blood pressure below the cerebral, renal, and/or coronary autoregulatory range will result in a marked reduction in organ blood flow, leading to ischemia and infarction.” – Pubmed


As with any prescription drug, patients who are prescribed Lisinopril should know how Lisinopril works before they take it. Patients should strive to learn as much as they can about the medications they take, including their effects, side effects, and any contraindications they may have with other drugs.

Discuss with your doctor any questions you may have regarding Lisinopril, and read the informational pamphlet that comes with your Lisinopril prescription. Often times your Pharmacy can give you information, but there are also a number of great resources online that allow you to learn more about how Lisinopril works.

Lastly, if you are looking to save up to 90% on your prescriptions, be sure to buy Lisinopril online, as you can save up to 90% off of your prescription drug costs. By educating yourself on how Lisinopril works and on how you can buy Lisinopril online for lower prices than are offered in US pharmacies, you can be an educated patient, and a patient who seeks the best deals possible.

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