Lisinopril is an ACE inhibitor, short for angiotensin-converting enzyme inhibitor. It’s one of the most commonly prescribed blood pressure medications in the United States, taken as a once-daily pill. ACE inhibitors work by blocking a specific enzyme that tightens blood vessels, allowing blood to flow more easily and reducing the workload on your heart.
How ACE Inhibitors Work
Your body has a built-in system for regulating blood pressure called the renin-angiotensin-aldosterone system. As part of this system, an enzyme converts a relatively inactive protein (angiotensin I) into a powerful blood vessel constrictor (angiotensin II). That constrictor does exactly what the name suggests: it squeezes blood vessels tighter, raising pressure. It also triggers your adrenal glands to release a hormone called aldosterone, which tells your kidneys to hold onto more sodium and water, further increasing blood volume and pressure.
Lisinopril blocks that conversion step. With less of the constricting chemical circulating, blood vessels relax and widen. Aldosterone levels drop, so your body retains less fluid. The net result is lower blood pressure and less strain on the heart. This is also why ACE inhibitors can raise potassium levels: aldosterone normally helps your kidneys excrete potassium, and when aldosterone drops, potassium can build up.
What Lisinopril Is Prescribed For
The FDA has approved lisinopril for three uses:
- High blood pressure in adults and children 6 years and older. This is by far the most common reason it’s prescribed. The usual maintenance dose ranges from 20 to 40 mg once daily, though most people start at 10 mg.
- Heart failure. Lisinopril is used alongside other medications to reduce symptoms of heart failure where the heart isn’t pumping strongly enough. Starting doses are lower here, typically 5 mg, and gradually increased.
- After a heart attack. In patients who are stable within 24 hours of a heart attack, lisinopril can reduce the risk of death.
The ACE Inhibitor Cough
The most distinctive side effect of ACE inhibitors, lisinopril included, is a persistent dry cough. It’s not dangerous, but it can be annoying enough that some people switch to a different medication. The cough happens because ACE doesn’t just convert angiotensin. It also breaks down a substance called bradykinin. When you block ACE, bradykinin accumulates in the lungs and airways, irritating them and triggering the cough reflex. Not everyone gets it, but if you develop a dry cough that won’t go away a few weeks after starting lisinopril, this is the likely explanation.
Angioedema: A Rare but Serious Reaction
A small number of people on ACE inhibitors develop angioedema, a rapid swelling of the face, lips, tongue, or throat. In a study of more than 145,000 patients taking an ACE inhibitor, about 0.5% developed this reaction. That’s roughly 1 in 200 people, which is uncommon but not negligible.
Certain groups face higher risk. Black patients are nearly three times more likely to develop ACE inhibitor-related angioedema compared to white patients. Women have about a 44% higher risk than men. People who regularly take NSAIDs like ibuprofen or naproxen alongside an ACE inhibitor also see their risk roughly double. If you notice sudden swelling of your face or throat while taking lisinopril, this requires immediate medical attention because it can obstruct breathing.
Potassium and Drug Interactions
Because lisinopril reduces aldosterone (the hormone that helps your kidneys flush out potassium), it can cause potassium levels to climb. For most healthy people, this isn’t a problem. But combining lisinopril with potassium supplements, potassium-sparing diuretics, or even potassium-containing salt substitutes can push levels into a dangerous range. Severely elevated potassium can cause muscle weakness, irregular heart rhythms, and in extreme cases, cardiac arrest.
The risk is highest if you have kidney disease, diabetes, or advanced heart failure. Regular use of NSAIDs like ibuprofen can compound the problem by impairing kidney function. Older adults and people who are dehydrated are also more vulnerable. If you take lisinopril alongside any of these medications, your doctor will likely monitor your potassium and kidney function through periodic blood tests.
Kidney Function and Dose Adjustments
Lisinopril is cleared through the kidneys, so people with reduced kidney function need lower starting doses. If your kidneys are filtering at more than 30 mL per minute (a measure of kidney efficiency called creatinine clearance), no adjustment is needed. Between 10 and 30 mL per minute, the starting dose is cut in half. For people on dialysis or with very poor kidney function below 10 mL per minute, the starting dose drops to 2.5 mg.
Pregnancy Warning
Lisinopril carries an FDA boxed warning, the most serious category of drug safety alert, regarding use during pregnancy. ACE inhibitors taken during the second and third trimesters can cause severe injury or death to the developing fetus. If you become pregnant while taking lisinopril, it should be stopped as soon as possible.
How Lisinopril Compares to Other Blood Pressure Drugs
ACE inhibitors are one of several major classes used to treat high blood pressure, alongside calcium channel blockers, beta-blockers, and ARBs (angiotensin receptor blockers). ARBs are the closest relative to ACE inhibitors. They target the same blood pressure system but block the action of angiotensin II at the receptor rather than preventing its creation. ARBs are less likely to cause the characteristic dry cough, which is why they’re a common alternative for people who can’t tolerate lisinopril.
Within the ACE inhibitor class itself, lisinopril is notable for being long-acting and taken once daily. It doesn’t need to be converted by the liver to become active, unlike some other ACE inhibitors, which makes its absorption more straightforward. It’s available as a generic, making it one of the more affordable options in its class.