Yes, lisinopril can cause diarrhea, and it is one of the complaints people report most often after starting the drug. For most people it is a nuisance rather than a danger. The cases worth taking seriously are the rare ones where diarrhea arrives with severe belly pain, a sign that the gut itself is reacting to the drug.
How Often Diarrhea Shows Up on Lisinopril
Lisinopril belongs to a drug family called ACE inhibitors, which relax blood vessels to lower blood pressure. In people taking lisinopril alone for high blood pressure, diarrhea was one of the four most frequent complaints, alongside headache, dizziness and cough.1PubMed. The safety and tolerability of lisinopril in clinical trials In people taking it for heart failure, diarrhea was again near the top, with dizziness, low blood pressure, tiredness, headache and rash.2PubMed. The safety and tolerability of lisinopril in clinical trials Not all of those complaints were judged to be caused by the drug itself, so diarrhea that starts after lisinopril may or may not be from the pill.3PubMed. The safety and tolerability of lisinopril in clinical trials
Trials count every complaint people have while on a drug, whatever the cause, and stomach bugs and diet changes cause diarrhea in anyone. A pattern of loose stools that start with the drug and stop without it is much stronger evidence than timing alone.
Mild lisinopril diarrhea usually looks like loose stools without severe pain, fever or blood. It often appears in the first days or weeks of treatment, and many people can keep eating and drinking normally.
To judge your own case, look at the calendar. Diarrhea that began within days to weeks of the first dose or a dose increase is more suspicious than diarrhea that began after months of steady use with no change. Then think about what else changed in that window, such as a sick household member, travel, a new supplement or a new medicine, because any of these can explain loose stools just as well. A short note of when stools were loose, what you ate and when you took each dose gives your prescriber something concrete to work with.
Among heart failure patients, about 1 in 10 (9.6%) stopped lisinopril because of side effects, with diarrhea among the reasons.4Consensus Academic Search Engine. Side Effects Of The Drug Lisinopril Yet some medical reviews still describe ACE inhibitor diarrhea as rare overall.5American Journal of Gastroenterology. S2793 Sprue-Like Enteropathy Secondary to Lisinopril Use
Heart failure patients often take several other medicines at once, including water pills, which gives diarrhea more possible sources. They can also be more vulnerable to fluid loss and low blood pressure, so loose stools that keep going deserve a call to the care team sooner.
Warning Signs That Need Urgent Care
When lisinopril swells the bowel, belly pain is present in every reported case.6PubMed Central. Angiotensin-converting enzyme inhibitor-induced bowel angioedema: clinical features, diagnostic challenges, and recovery predictors from survival analysis: a systematic review of current reported cases About 3 in 4 people have nausea and two thirds vomit, while fewer than half have diarrhea.7PubMed Central. Angiotensin-converting enzyme inhibitor-induced bowel angioedema: clinical features, diagnostic challenges, and recovery predictors from survival analysis: a systematic review of current reported cases Go to urgent care or an emergency department for severe or worsening belly pain on lisinopril, and tell them you take it.
Ordinary diarrhea tends to come with cramping that eases after a bowel movement. The worrying pain is intense, steady or worsening, and it doesn’t let up. Pain severe enough to make you double over, stop you from eating, or keep you from finding a comfortable position shouldn’t be waited out at home. Vomiting that keeps you from holding down fluids, along with belly pain, is a reason to be seen the same day rather than treating it as a stomach bug. Blood in the stool, black stools, or a fever alongside the pain also call for prompt medical evaluation, whatever the cause turns out to be.
The same drug family can cause swelling of the lips, tongue or throat, which can block breathing. Call emergency services for any throat swelling or trouble breathing.
Dehydration deserves attention too. Dizziness on standing, very dark urine or passing very little urine are signs you are losing too much fluid. Lisinopril already lowers blood pressure, so fluid loss can make dizziness worse, and older adults and people on water pills dehydrate faster. Sip fluids with salts, such as oral rehydration drinks, and seek care if you can’t keep up with the losses. If you seek care, tell the doctor when you started lisinopril and at what dose, whether you have had similar belly attacks before, and about any other new medicines or recent illness.
The Rare Bowel Swelling Reaction
This reaction is a swelling of the bowel wall, and doctors may call it intestinal angioedema. It happens because ACE inhibitors let a natural chemical build up, which makes blood vessels leaky so fluid seeps into the gut wall.8Cureus. Angiotensin-Converting Enzyme Inhibitor-Associated Hypersensitivity Vasculitis With Small Bowel Edema: A Case Report Among reported cases from this drug family, lisinopril was involved in about 7 in 10, largely because it is so widely prescribed.9PubMed Central. Angiotensin-converting enzyme inhibitor-induced bowel angioedema: clinical features, diagnostic challenges, and recovery predictors from survival analysis: a systematic review of current reported cases
The typical case is a middle-aged woman who recently started an ACE inhibitor and develops belly pain, vomiting and diarrhea.10PubMed. Angiotensin-converting enzyme inhibitor angioedema of the intestine: a case report and review of the literature In one reported case, symptoms began just two days after starting lisinopril 20 mg.11Journal of Hospital Medicine. Blood Pressure Medication Gives A Punch To The Gut: Unmasking Lisinopril Induced Intestinal Angioedema Attacks can also be recurrent, coming and going.12Consensus Academic Search Engine. Lisinopril And Gastrointestinal Side Effects On a CT scan the bowel looks swollen, and fluid may collect in the belly.13PubMed Central. Lisinopril-Induced Small Bowel Angioedema: An Unusual Cause of Severe Abdominal Pain
An attack usually brings sudden, crampy pain, often across the middle or lower belly, strong enough to send someone to the emergency room. Vomiting and nausea tend to dominate, and diarrhea may be watery or absent altogether. The reaction usually settles over a day or two once the drug is stopped, though people may need fluids in hospital while they recover.
It is often missed. Belly symptoms can be the only clue; having no puffy lips doesn’t rule out bowel swelling. The symptoms look like a stomach bug or food poisoning, and doctors may not link a blood pressure pill to the gut. Some people make repeated ER visits before the drug is suspected, so saying “I take lisinopril” early can speed diagnosis.
It can also start months or years after the first dose. Swelling reactions from this drug family don’t always appear in the first days, and having taken it safely for a long time doesn’t rule it out. Recurrent unexplained belly attacks on lisinopril deserve a review.
No single blood test confirms it, so doctors rely on the story, the exam and imaging, with a CT scan the usual way to see the swollen bowel. They look for other causes of severe belly pain first, such as blockage, infection or appendicitis, which is part of why diagnosis can take time. The strongest confirmation is often that the pain and swelling resolve after the drug is stopped. Once it is suspected, the key step is stopping the drug, not adding more tests while it continues.
Stopping Lisinopril and How Fast Diarrhea Clears
When an ACE inhibitor is causing diarrhea, symptoms typically improve within 24 to 48 hours after stopping it.14Canadian Family Physician. Diarrhea induced by angiotensin-converting enzyme inhibitors But stopping without a replacement can let blood pressure rise, so call your prescriber the same day rather than quietly skipping doses.
The right move depends on who you are. For heart failure patients, stopping lisinopril abruptly can let symptoms worsen, so the call should happen the same day and the replacement plan should be clear. For mild diarrhea with no warning signs, a prescriber may be comfortable watching for a few days rather than changing anything. If severe belly pain or swelling is present, the usual advice is to seek urgent care rather than wait for a phone appointment.
When you call, describe how many loose stools you have had, how long this has gone on, and whether there is any belly pain, vomiting, fever or dizziness. Say exactly when you started lisinopril and whether the dose recently changed, since timing is the most useful clue. Ask directly whether to take your dose today, since the right answer depends on how sick you are and why you take it.
The prescriber may keep the drug if the diarrhea is mild and short-lived, or switch you to a different class of blood pressure medicine. After a bowel swelling reaction, they will avoid all drugs in the family, since they share the same effect, and should record the reaction in your chart as a drug allergy.
Meanwhile, drink plenty of fluids. Ask a pharmacist before taking anti-diarrhea medicine, and check your blood pressure at home if you feel dizzy.
Other Possible Causes of Diarrhea on Lisinopril
Some tablets contain lactose as a filler, and medication lactose can cause diarrhea, cramping or bloating in sensitive people.15Journal of Pharmacy Technology. In Search of Lactose If you are lactose intolerant, ask a pharmacist whether your brand contains it. Fillers differ between manufacturers, so mention it if diarrhea began right after a refill that looked different from your usual pills.
Rarely, lisinopril has caused damage to the gut lining that resembles celiac disease, leading to ongoing diarrhea and poor absorption of food.16American Journal of Gastroenterology. S2793 Sprue-Like Enteropathy Secondary to Lisinopril Use This reaction is slow and persistent, building over weeks to months rather than starting abruptly and fading in days. People may lose weight, feel tired or become low in nutrients. Weight loss or diarrhea lasting weeks needs testing, and a doctor may check for celiac disease and gut lining damage. Improvement after stopping the drug helps confirm it.
ACE inhibitors and related drugs can also shift the mix of gut bacteria.17PubMed Central. Antihypertensive Therapy by ACEI/ARB Is Associated With Intestinal Flora Alterations and Metabolomic Profiles in Hypertensive Patients Whether those changes cause symptoms is not known. Plenty of unrelated things cause diarrhea too: stomach viruses and food poisoning, other new drugs such as metformin or antibiotics, combination pills that add a water pill, and diet changes made after a new diagnosis.
Lisinopril has also been linked to inflammation of the pancreas, which causes belly pain and vomiting, sometimes without diarrhea.18Journal of the American Board of Family Practice. Drug-Induced Pancreatitis (Lisinopril) Pancreas pain tends to sit in the upper belly, may be felt through to the back, and is often worse after eating. Because diarrhea may be absent, belly pain with vomiting on lisinopril needs urgent assessment and is worth reporting either way.
Do Other Blood Pressure Pills Cause Diarrhea
A related family, ARBs, is a common switch for people who can’t take ACE inhibitors. ARBs lower blood pressure by blocking a related pathway but don’t let that chemical build up the way lisinopril’s family does, so swelling reactions are much less likely, though not impossible. Doctors often choose an ARB for people who had cough or other trouble on lisinopril, and the protective effect on the heart in heart failure is similar. Even so, a person who had a serious swelling reaction needs the prescriber to decide carefully.
One ARB, olmesartan, has long been documented to cause diarrhea and gut lining damage.19Side Effects of Drugs Annual. Side effects of antihypertensive drugs Other ARBs such as losartan and valsartan have been linked to diarrhea only in scattered reports, without proof they cause it.20Side Effects of Drugs Annual. Side effects of antihypertensive drugs If diarrhea was a problem, ask whether an ARB other than olmesartan or a different class suits you.
Calcium channel blockers and water pills work differently and don’t share the swelling mechanism. Each has its own side effects to discuss, and blood pressure should be monitored closely in the first weeks after a switch.
Tell the prescriber about the diarrhea history so the next choice avoids a known culprit such as olmesartan. If loose stools return after a switch, note the timing again, because the pattern helps show which drug is responsible.
Water pills can cause frequent urination and low potassium or sodium, so unusual weakness or cramps should be reported. Calcium channel blockers commonly cause ankle swelling, which is different from the dangerous swelling of the face or throat but still worth mentioning to the prescriber.