Features October 2009 Issue

What You Need to Know About ACE Inhibitors

These drugs reduce the workload on the heart by helping to dilate blood vessels.

Angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Altace), lisinopril (Prinivil) and captopril (Capoten) are used to treat a variety of cardiovascular-related issues, including high blood pressure, heart failure and stroke, and also improve survival in people following a heart attack. They also may be given to treat migraine and the autoimmune disease scleroderma if it is affecting the heart. And new research (Archives of Internal Medicine, July 13) suggests the drugs may reduce the inflammation that is thought to be a factor in Alzheimer’s disease.

ACE inhibitors work by relaxing the blood vessels. In order to achieve this effect, they inhibit the activity of ACE, which converts a naturally occurring chemical called angiotensin I into angiotensin II. Angiotensin II causes the muscles surrounding the blood vessels to contract, thereby narrowing the vessels, which means the heart has to work harder to pump blood.

Because ACE inhibitors decrease production of angiotensin II, the blood vessels are able to dilate and blood pressure is reduced, meaning less work for the heart. As well as taking the pressure off where heart disease is concerned, this also may slow the progression of kidney disease due to high blood pressure or diabetes.

Possible Side Effects

ACE inhibitors are typically well-tolerated, but they aren’t completely free of side effects. Common examples include a persistent dry cough, dizziness (get up slowly from a sitting or prone position to avoid falls), headaches, weakness, a rash and a reduced appetite. They also may cause elevated potassium levels (known as hyperkalemia). While potassium aids in heart function, too much can raise the risk of heart arrhythmias (irregular heartbeat), which can potentially be fatal.

Rarely, ACE inhibitors can cause swelling (angioedema)—most likely to occur in African–Americans and smokers. If it occurs in the throat, this can be life-threatening. Kidney failure is another rare side effect.

Important Precautions

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin, others) and naproxen (Aleve, others) decrease the effectiveness of ACE inhibitors, so if you need to take these medications regularly for another health issue such as arthritis, be sure to inform your doctor.

ACE inhibitors also may increase the blood concentration of lithium, so if you take this medication to treat bipolar disorder (also known as manic depression), be sure to tell your doctor.

Since ACE inhibitors may raise potassium levels, you should avoid using potassium-based salt substitutes. If you take other medications, check with your doctor that none of these also raise potassium levels. You may also be advised to limit your consumption of potassium-rich foods such as bananas, oranges, tomatoes, dried peas and beans, nuts, potatoes, and avocados. Avoid taking multivitamin supplements that contain potassium.

People with bilateral renal artery stenosis (narrowing of the arteries that carry blood from the heart to the kidneys) may experience worsening of kidney function if taking ACE inhibitors, and people who have had a severe reaction to ACE inhibitors also should avoid them.


If you cannot tolerate ACE inhibitors, your doctor may recommend an angiotensin-receptor blocker (ARB). These drugs block receptors for angiotensin II.