ACE Inhibitors and ARBs: How These Medications Protect Your Heart and Kidneys
ACE inhibitors and ARBs are two of the most widely prescribed blood pressure drugs in the world. They work through the same hormonal pathway, which causes a lot of confusion. But they have real differences, and knowing them can help you have a smarter conversation with your doctor.
The System They Both Target
Your kidneys produce an enzyme called renin when blood pressure drops or blood flow decreases. Renin kicks off a chain reaction: it converts a protein in your blood into angiotensin I, which then gets converted into angiotensin II by an enzyme called ACE (angiotensin-converting enzyme).
Angiotensin II is a potent vasoconstrictor. It tightens blood vessels and signals the body to retain sodium and water. Both of these actions push blood pressure up.
ACE inhibitors block the enzyme that makes angiotensin II. ARBs take a different approach: they let angiotensin II form, but block the receptor it needs to bind to. Either way, blood vessels relax, and blood pressure comes down.
The renin-angiotensin system (RAS) doesn’t just regulate blood pressure. It also drives inflammation and fibrosis in the kidneys and heart. Blocking it protects both organs over time, not just in the short term.
ACE Inhibitors: The First-Line Standard
ACE inhibitors are often prescribed first because they’ve been around for decades, are well-studied, and are available as cheap generics. Common ones include lisinopril, enalapril, ramipril, and benazepril.
The HOPE trial, published in the New England Journal of Medicine in 2000, followed over 9,000 high-risk patients for five years. Those who took ramipril had significantly fewer heart attacks, strokes, and cardiovascular deaths compared to those on placebo. [1]
That trial helped cement ACE inhibitors as a cornerstone of cardiovascular care, not just for blood pressure control, but for people at high cardiac risk even without hypertension.
ARBs: The Well-Tolerated Alternative
ARBs came along later. Common ones include losartan, valsartan, olmesartan, and irbesartan. They produce similar blood pressure reductions to ACE inhibitors, with one important advantage: they don’t cause the cough.
Because ARBs work by blocking the receptor rather than the enzyme, they don’t interfere with bradykinin (more on that below). Doctors typically prescribe them when a patient can’t tolerate an ACE inhibitor, or in certain kidney conditions where ARBs have the stronger evidence base.
The ACE Inhibitor Cough
Between 10 and 20 percent of patients who take an ACE inhibitor develop a dry, persistent cough. It can range from mildly annoying to disruptive enough to affect sleep. Women and people of East Asian descent tend to be more affected.
The mechanism: ACE inhibitors cause bradykinin to accumulate in the airways, which triggers the cough reflex. ARBs don’t block ACE, so bradykinin stays at normal levels and the cough doesn’t happen.
If you develop a cough on an ACE inhibitor, your doctor will almost always switch you to an ARB. The blood pressure control is comparable, and most patients tolerate the switch well.
Up to 1 in 5 patients experience it. It’s the most common reason people stop taking their ACE inhibitor. If you notice a new persistent cough after starting one of these medications, tell your doctor. Switching to an ARB typically resolves it within a few weeks.
Why These Drugs Matter for Kidneys
Blood pressure medications aren’t all equal when it comes to the kidneys. ACE inhibitors and ARBs have a specific protective effect that other drug classes don’t replicate as well.
In diabetic nephropathy (kidney disease caused by diabetes), elevated blood pressure inside the kidney’s tiny filtering units (glomeruli) accelerates damage. Both drug classes reduce this intraglomerular pressure directly, slowing the progression of kidney disease independent of their effect on systemic blood pressure.
The RENAAL trial tested this in patients with type 2 diabetes and established nephropathy. Patients who took losartan had significantly lower rates of kidney failure, dialysis, and transplant compared to those on placebo, even after adjusting for blood pressure differences. [2]
A 2015 analysis in JAMA Internal Medicine confirmed the kidney-protective benefit of RAAS inhibitors broadly, finding consistent reductions in end-stage kidney disease risk across patient populations. [3]
For diabetic patients who have protein in their urine, ACE inhibitors or ARBs are often prescribed even when blood pressure is normal. The goal isn’t just pressure control. It’s organ protection.
Important Precautions
Both drug classes are off the table during pregnancy. They can cause serious fetal harm, including kidney malformation and death. Women of childbearing age who are prescribed these medications should use effective contraception and inform their doctor immediately if they become pregnant.
Both classes can raise potassium levels. This is usually mild and manageable, but in patients with chronic kidney disease, potassium can climb to dangerous levels. Your doctor will typically monitor your labs after starting or adjusting these medications.
ACE inhibitors carry a small risk of angioedema: sudden swelling of the face, lips, tongue, or throat. It’s rare, but it can be life-threatening and requires emergency care. If you experience any facial or throat swelling while on an ACE inhibitor, call 911.
One more practical note: NSAIDs (ibuprofen, naproxen) blunt the effectiveness of both drug classes and add kidney stress. If you’re on an ACE inhibitor or ARB, avoid regular NSAID use. Talk to your doctor about safer alternatives for pain management.
Frequently Asked Questions
Can I take an ACE inhibitor and an ARB together?
Generally, no. Combining them was studied in several trials and found to increase the risk of kidney problems and high potassium without meaningful added benefit. Most guidelines advise against dual RAAS blockade outside of very specific clinical situations managed by a specialist.
How long does it take for these medications to lower blood pressure?
You may see some effect within a few hours of the first dose, but the full blood pressure response typically takes two to four weeks. Your doctor will usually schedule a follow-up to check your numbers and adjust the dose if needed.
If I feel fine, do I still need to keep taking my ACE inhibitor or ARB?
Yes. High blood pressure usually has no symptoms, and neither does the kidney damage it causes. These medications work in the background to prevent events like heart attacks, strokes, and kidney failure. Stopping them because you “feel fine” removes that protection. Always talk to your doctor before making any changes.
Are there foods I should avoid while on these medications?
Salt substitutes are a big one. Many contain potassium chloride instead of sodium chloride, and since ACE inhibitors and ARBs already raise potassium, adding a salt substitute can push levels too high. Potassium-rich foods (bananas, oranges, potatoes) are generally fine in normal amounts, but check with your doctor if you have kidney disease.
What’s the difference between ACE inhibitors and beta-blockers for blood pressure?
They work completely differently. Beta-blockers slow your heart rate and reduce the force of each beat. ACE inhibitors work on the hormonal system that controls vessel constriction. Many patients end up on both because they target different mechanisms. Your doctor’s choice depends on your specific conditions, including whether you have heart failure, coronary artery disease, or kidney disease.
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Clinical References
- Yusuf S, et al. Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients. N Engl J Med. 2000. PMID: 10639539
- Brenner BM, et al. Effects of losartan on renal and cardiovascular outcomes in patients with type 2 diabetes and nephropathy. N Engl J Med. 2001. PMID: 11565518
- Heerspink HJ, et al. Kidney outcomes associated with use of RAAS inhibitors in patients with hypertension. JAMA Intern Med. 2015. PMID: 25602195
These statements have not been evaluated by the Food and Drug Administration. This content is for informational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Always consult your healthcare provider before making changes to your medications or supplement routine.