Potassium Risk Calculator for ACE Inhibitors and ARBs
Personal Information
When doctors prescribe blood pressure meds, they often choose between ACE inhibitors and ARBs. Both work on the same system in your body-the renin-angiotensin system-to lower blood pressure and protect your kidneys and heart. But theyâre not the same. And mixing them? Thatâs where things get risky.
How ACE Inhibitors and ARBs Work
ACE inhibitors like lisinopril, enalapril, and ramipril stop your body from making angiotensin II, a chemical that tightens blood vessels and raises blood pressure. They do this by blocking the enzyme that turns angiotensin I into angiotensin II. Simple enough.
ARBs-losartan, valsartan, irbesartan-take a different route. Instead of stopping angiotensin II from being made, they block its receptors. Think of it like locking the door so angiotensin II canât get in, even if itâs still around.
This small difference matters. ACE inhibitors can cause a buildup of bradykinin, which leads to a dry, annoying cough in 10-15% of people. ARBs donât do that. Thatâs why if you canât tolerate an ACE inhibitor, your doctor will switch you to an ARB. Itâs the go-to alternative.
Why People Think About Combining Them
It makes sense on paper. If one drug blocks angiotensin II in one way, and another blocks it in another, wouldnât two be better than one? Especially if you have diabetes and kidney disease, where protein in the urine (proteinuria) is a big problem?
Some studies did show that combining them lowered blood pressure by another 3-5 mmHg and cut proteinuria by about 25%. That sounds great-until you look at what else happens.
The Real Danger: Hyperkalemia and Kidney Damage
The biggest problem with mixing ACE inhibitors and ARBs is hyperkalemia-dangerously high potassium levels. Your kidneys normally flush out extra potassium. But both drugs reduce the hormone that tells your kidneys to do that. When you take both, your potassium can climb fast.
In the ONTARGET trial, which followed over 25,000 high-risk patients, those on both drugs had a 5.5% chance of developing severe hyperkalemia compared to 2.5% on just an ACE inhibitor. Thatâs more than double. And itâs not just numbers. High potassium can cause irregular heartbeats, muscle weakness, even cardiac arrest.
Then thereâs kidney damage. The same trial found that 2.3% of patients on the combo needed dialysis because their kidneys failed. Thatâs more than twice the rate of those on ACE inhibitors alone. The VA NEPHRON-D trial confirmed this: combining the two increased serious kidney events by 27% without improving survival or heart outcomes.
Real-world data backs this up. A nephrologist at Massachusetts General Hospital stopped the combo in 87% of her patients with diabetic kidney disease because of rising potassium or dropping kidney function. Medical residents on Reddit reported seeing hospitalizations for hyperkalemia linked to this combo during rotations.
When Is It Ever Okay?
Almost never. Major guidelines from the American Heart Association, the American College of Cardiology, and the European Society of Cardiology all say: avoid combining ACE inhibitors and ARBs outside of clinical trials.
Thereâs one tiny exception some experts mention: non-diabetic patients with very high proteinuria (over 1 gram per day) who havenât responded to the highest dose of an ACE inhibitor. Even then, itâs not standard. It requires weekly blood tests, close monitoring, and a clear plan to stop if potassium rises or kidney function dips.
Dr. Srinivasan Beddhu from the University of Utah says this might help in rare cases of focal segmental glomerulosclerosis. But even he warns itâs not for everyone. And in 2023, a survey of 317 primary care doctors found only 11% still used the combo-mostly in those rare cases with monthly labs.
What to Do Instead
If you need stronger blood pressure control or better kidney protection, there are safer options.
- Switch from an ACE inhibitor to an ARB if you have a cough.
- Upgrade your dose-sometimes the problem isnât the drug, itâs the dose.
- Add a low-dose diuretic like chlorthalidone or indapamide. These help flush out fluid and potassium.
- Consider a mineralocorticoid receptor antagonist like spironolactone (12.5 mg daily). It reduces proteinuria by 30-40% with fewer kidney risks than combining ACE inhibitors and ARBs.
And if youâre on one of these drugs and your blood pressure isnât controlled? Donât add the other. Talk to your doctor about newer options like ARNIs (angiotensin receptor-neprilysin inhibitors), which have shown better outcomes in heart failure and are now preferred over dual RAS blockade.
Switching Between Them
If your doctor wants to switch you from an ACE inhibitor to an ARB-or vice versa-donât just swap them on the same day. You need a washout period.
Most guidelines recommend waiting at least 4 weeks between switching. Why? Because even after you stop one, the drug stays in your system. Starting the other too soon can lead to additive effects, increasing your risk of low blood pressure, kidney problems, or high potassium.
But hereâs the problem: only 42% of doctors actually follow this rule, according to a 2022 JAMA Internal Medicine study. If youâre switching, make sure your doctor knows to wait. And if youâre unsure, ask for a blood test two weeks after the switch to check your potassium and kidney function.
Monitoring Is Non-Negotiable
No matter which drug youâre on, you need regular blood tests. The first one should be 1-2 weeks after starting or changing the dose. Then every 3 months if youâre stable.
What to check:
- Serum potassium (normal is 3.5-5.0 mmol/L; above 5.5 is dangerous)
- Serum creatinine (to estimate kidney function)
- eGFR (estimated glomerular filtration rate)
If your potassium goes up by more than 0.5 mmol/L or your creatinine rises by 30%, your doctor needs to adjust your treatment. Thatâs not a minor bump-itâs a red flag.
Why This Still Happens
Even with all the evidence, some patients still end up on both drugs. Why?
- Doctors might think, âTheyâre not responding to one, so letâs add another.â
- Patients hear âit lowers proteinuriaâ and assume itâs a win.
- Some specialists, especially nephrologists, are more tempted to try it in tough cases.
But the data is clear: the risks outweigh the benefits. And with better alternatives available-like ARNIs, SGLT2 inhibitors for diabetes, or newer potassium binders-thereâs no reason to take this gamble.
The Bottom Line
ACE inhibitors and ARBs are both powerful, proven tools. But theyâre not meant to be used together. The idea that more is better doesnât apply here. In fact, combining them can be dangerous.
If youâre on one and your blood pressure isnât under control, donât reach for the other. Talk to your doctor about dose adjustments, adding a diuretic, or switching to a newer class of drugs.
If youâre already on both, ask: Why? Whatâs the plan? When was your last potassium test? And if you canât answer those questions, itâs time to have a serious conversation with your provider.
Your kidneys and your heart donât need extra stress. They need smart, safe choices.
Can I take an ACE inhibitor and an ARB together for better blood pressure control?
No. Combining ACE inhibitors and ARBs is not recommended. While it may lower blood pressure slightly more, it doubles the risk of hyperkalemia and increases the chance of acute kidney injury. Major guidelines from the AHA, ACC, and ESC strongly advise against this combination due to serious safety risks without proven benefits in survival or heart protection.
Why do ACE inhibitors cause a cough but ARBs donât?
ACE inhibitors block the enzyme that breaks down bradykinin, a substance that can irritate the airways and cause a dry, persistent cough. ARBs donât affect bradykinin levels-they only block angiotensin II receptors-so they rarely cause this side effect. About 10-15% of people on ACE inhibitors get the cough; only 3-5% do on ARBs.
What should I do if Iâm currently taking both an ACE inhibitor and an ARB?
Donât stop either medication on your own. Contact your doctor immediately. You may need a blood test to check your potassium and kidney function. Most patients on this combination will be switched to one drug, with alternatives like diuretics or spironolactone added if needed. Your doctor may also consider newer options like ARNIs or SGLT2 inhibitors depending on your condition.
Is it safe to switch from an ACE inhibitor to an ARB?
Yes, switching is common and safe if done correctly. Wait at least 4 weeks after stopping the ACE inhibitor before starting the ARB. This prevents overlapping effects that could cause low blood pressure or kidney stress. Your doctor should check your potassium and creatinine 1-2 weeks after the switch to make sure youâre stable.
Are ARBs safer than ACE inhibitors overall?
ARBs are better tolerated because they donât cause cough or angioedema as often. However, ACE inhibitors have stronger evidence for reducing death in heart failure. Neither is universally âsaferâ-it depends on your condition. For example, if you have heart failure with reduced ejection fraction, ACE inhibitors are preferred. If you have a cough or are at high risk for swelling, ARBs are the better choice.
What are the signs I might have high potassium from these drugs?
High potassium often has no symptoms at first. But as it rises, you might feel muscle weakness, fatigue, irregular heartbeat, nausea, or tingling in your hands or feet. In severe cases, it can cause cardiac arrest. Regular blood tests are the only reliable way to catch it early. If youâre on an ACE inhibitor or ARB, get your potassium checked every 3 months-or sooner if your dose changes.
Why were some ARBs recalled in 2018-2020?
Some ARBs like valsartan, losartan, and irbesartan were recalled because they contained trace amounts of nitrosamine impurities-chemicals that could increase cancer risk over long-term exposure. These were manufacturing byproducts, not inherent to the drugs. Most manufacturers fixed their processes by late 2023, and current supplies are considered safe. Always check with your pharmacist if youâre concerned about your specific batch.
Are there any new drugs replacing ACE inhibitors and ARBs?
Yes. ARNIs (like sacubitril/valsartan) are now preferred for heart failure with reduced ejection fraction because theyâve been shown to reduce death and hospitalizations better than ACE inhibitors alone. SGLT2 inhibitors (like dapagliflozin and empagliflozin) are also now recommended for patients with diabetes and kidney disease, even without high blood pressure, because they protect the heart and kidneys. These are replacing the need for risky combinations.
Whatâs Next?
If youâre managing high blood pressure or kidney disease, your treatment doesnât have to be stuck in the past. The era of combining ACE inhibitors and ARBs is ending-not because the drugs donât work, but because we now know safer, more effective ways to protect your body.
Ask your doctor: Is my current plan based on the latest guidelines? Are there newer options I havenât tried? And most importantly-am I being monitored properly?
Your health isnât about taking more pills. Itâs about taking the right ones-and knowing when to stop.
Reviews
man i just got switched from lisinopril to losartan last month cause of that damn cough - thought i was gonna lose my mind from it, like every time i laughed or talked i sounded like a broken foghorn đ
the arb thing is legit, no cough, no drama. my bpâs actually better too. weird how such a small change made such a big difference.
also, my doc told me to wait 4 weeks before switching but i was impatient and did it in 2 weeks⌠totally regretted it. dizzy as hell for two days. lesson learned.
and yeah, iâm now on chlorthalidone 12.5mg and itâs been smooth sailing. no more potassium scares. i check it every 3 months like they said. just a quick finger prick at the pharmacy.
also, my buddy on dialysis? he was on both drugs for a year. turned into a medical nightmare. potassium hit 6.8. they had to pump him full of insulin and glucose just to keep him alive. i donât wanna be that guy.
so yeah, donât combo. just donât. thereâs better ways. like that new sglt2 stuff. my endoâs pushing it on me next. sounds like magic.
also, i used to think more meds = better. now i know itâs like adding more pillows to your bed until you canât breathe. simple is better.
i think this is so important and i wish more people knew this
my mom was on both and her kidneys took a hit and she ended up in the hospital
they had to pull her off both and now sheâs on a diuretic and itâs way safer
just please listen to the guidelines
you know whatâs wild? weâve been treating hypertension like itâs a puzzle where more pieces = better picture
but the bodyâs not a math equation
itâs a living system that hates redundancy and loves balance
ace inhibitors and arbs are like two people trying to turn the same knob from opposite sides
oneâs pushing the door shut, the otherâs jamming the lock
itâs not synergy, itâs chaos
and the real tragedy? weâve had better tools for years - sglt2 inhibitors, arnis, even spironolactone at low doses
but doctors keep reaching for the old tools because theyâre familiar
and patients? we trust them
so we donât ask questions
we just swallow the pills
but if your doctor hasnât mentioned sglt2 inhibitors or arnis by now⌠maybe itâs time to find a new one
your kidneys arenât just filters
theyâre your silent partners
treat them like they matter
as an irish GP, iâve seen this play out too many times
patients come in with proteinuria, we add the arb on top of the ace, think weâre being clever
then come back 6 weeks later with creatinine through the roof and potassium at 6.2
weâve got better options now
why risk it?
the dataâs clear
and honestly, the guilt when you have to tell someone they need dialysis because we over-treated them?
not worth it
Thank you for sharing this đ
Iâve been on lisinopril for 5 years and just learned last month that combining it with an ARB is risky.
Iâm so glad I asked my doctor before making any changes.
Now Iâm on a low-dose diuretic and my numbers are better than ever!
Knowledge is power - and safety â¤ď¸
my dadâs on an arb and he swears by it - no cough, no fuss
but he also checks his potassium every 3 months like clockwork
he says itâs not about the drug, itâs about the habit
and honestly? heâs right
the real win isnât the pill
itâs the checkups
the blood tests
the conversations
the not-ignoring-the-small-things
thatâs what keeps you alive
Don't combine.
Check potassium.
Wait 4 weeks.
Use diuretics.
Ask about SGLT2.
if youâre on both, stop. now.
not tomorrow.
not after your next appointment.
call your doctor today.
youâre not being proactive - youâre being reckless.
hyperkalemia doesnât warn you.
it just kills you.
and your doctor probably didnât even realize you were on both.
you need to be the advocate.
your life isnât a clinical trial.
itâs your one shot.
donât gamble it.
oh my god
i just realized⌠weâve been treating the renin-angiotensin system like itâs a broken radio we can just twist both knobs until the static stops
but itâs not a radio
itâs a symphony
and when you add two conductors
the orchestra doesnât get louder
it collapses
and then your kidneys⌠your heart⌠your very soulâŚ
they scream
in silence
until itâs too late
weâve been so obsessed with âmoreâ
that we forgot what âenoughâ looks like
and now weâre paying with dialysis
with cardiac arrest
with funeral costs
and nobodyâs even apologizing
just prescribing more pills
the RAS blockade paradigm shift is long overdue
the 2023 ESC guidelines explicitly classify dual RAS inhibition as Class III recommendation - not recommended
and yet, 11% of PCPs still prescribe it
the cognitive dissonance is staggering
weâve got RCTs like ONTARGET and NEPHRON-D with n >25k
and still, anecdotal âbut my patient had lower proteinuriaâ
correlation â causation, and harm â benefit
the real win is mortality reduction
not proteinuria
and ARNIs have proven superior in PARADIGM-HF
so why are we still clinging to 1990s protocols?
because inertia
and laziness
and fear of change
not science
my cousin in canada got switched from lisinopril to valsartan and said he felt like a new person
no cough no problem
but he never checked his potassium
ended up in er with weird heartbeat
they said it was from high k
so now he does monthly tests
and heâs fine
just gotta be careful
and use the new drugs if you can
like sglt2
theyâre game changers
in india we have so many diabetic patients with kidney disease
doctors here still combine ace and arb because they think itâs âbetter controlâ
they donât know the trials
they donât care about potassium
they just give the pill
and the patient dies
and no one says anything
but i will say it
you are killing them with kindness
stop it
use spironolactone
use sglt2
use diuretics
but never both
why are people still on this combo in 2024?
are you serious?
youâre literally playing russian roulette with your kidneys
and you call yourself educated?
the data is 15 years old
the guidelines are crystal clear
youâre not special
youâre not the exception
youâre just another statistic waiting to happen
get off both
and get educated
or die
you think this is just about blood pressure?
no
this is about the collapse of modern medicine
we used to fix things
now we just stack pills
and call it progress
weâre not healing
weâre just delaying the inevitable
and calling it âmanagementâ
and the worst part?
weâre proud of it
we wear our prescriptions like medals
but your kidneys? theyâre not impressed
theyâre just⌠tired
been on losartan for 8 years
no cough
no drama
just check potassium every 3 months
and youâre golden
simple
effective
why make it hard?
wait i just saw someone say theyâre on both
bro thatâs wild
youâre basically playing dice with your kidneys
my doc almost fired me when i asked about switching
like⌠why are you even asking? itâs not a debate
but iâm glad i did
now iâm on sglt2 and i feel like iâve got my energy back
who knew the answer wasnât more pills?
it was better ones