Diarrhea is a common complaint among people on dialysis, and it shows up more often with hemodialysis than with home peritoneal dialysis. The machine itself is rarely the direct cause. The usual culprits are what kidney failure does to the gut, the medicines that come with dialysis, and infections. What sets it apart from ordinary diarrhea is that people on dialysis have little margin for losing fluid, so even a few bad days matter more.
How Common Diarrhea Is on Dialysis
About 19% of people starting hemodialysis have diarrhea.1Renal Replacement Therapy. Prevalence of diarrhea in end-stage renal disease patients initiating hemodialysis In a comparison of dialysis types, about 18% of hemodialysis patients reported it, versus about 5% of those on peritoneal dialysis.2PubMed Central. Gastrointestinal symptoms: A comparison between patients undergoing peritoneal dialysis and hemodialysis Stomach and bowel complaints of some kind affected about 7 in 10 people with kidney failure, and more of them were on hemodialysis.3PubMed Central. Gastrointestinal symptoms: A comparison between patients undergoing peritoneal dialysis and hemodialysis About 15% of hemodialysis patients had more than three gut symptoms at once, twice the share on peritoneal dialysis.4PubMed Central. Gastrointestinal symptoms: A comparison between patients undergoing peritoneal dialysis and hemodialysis People under 70 starting dialysis report diarrhea more often than older people.5Oxford Academic (Nephrology Dialysis Transplantation). Health-related quality of life and symptom burden in patients on haemodialysis
Loose stools are not the only bowel problem. Hemodialysis patients also report more constipation, about 36%. Fluid limits and binders often cause it, so one person may swing between the two depending on medicines and diet. Telling your care team which pattern you have helps them find the cause.
Kidney Failure and Medicines as Causes
Advanced kidney disease can inflame the bowel and weaken its lining, as seen in people and in animals.6PubMed Central. CKD impairs barrier function and alters microbial flora of the intestine: a major link to inflammation and uremic toxicity It also shifts the mix of gut bacteria, which then make waste products the failing kidneys can’t clear.7PubMed Central. CKD impairs barrier function and alters microbial flora of the intestine: a major link to inflammation and uremic toxicity
A weakened lining absorbs water and nutrients less well, so more fluid stays in the stool. Irritated tissue also moves its contents along faster, leaving less time for water to be taken back in. This kind of diarrhea tends to be on and off and long-running, unlike an infection that starts suddenly and often brings fever.
Medicines are another frequent cause. A phosphate binder is a pill taken with meals to stop the body absorbing phosphorus from food. With one iron-based binder, about 20% of dialysis patients got diarrhea, versus about 8% on a common alternative.8PubMed Central. A phase III study of the efficacy and safety of a novel iron-based phosphate binder in dialysis patients That diarrhea usually began early and settled without stopping the drug.9PubMed Central. A phase III study of the efficacy and safety of a novel iron-based phosphate binder in dialysis patients The same binder also darkened stools in about 15% of users, which is expected, not bleeding.10PubMed Central. A phase III study of the efficacy and safety of a novel iron-based phosphate binder in dialysis patients A newer potassium binder caused diarrhea in about 7% of users, usually mild.11Renal and Urology News. Potassium Binder May Also Lower Phosphate Levels in CKD
If you suspect a pill, write down the date the diarrhea started next to any medicine change. Binder diarrhea tends to begin in the first weeks. Don’t stop a binder on your own, since phosphorus can climb. Ask instead whether a different binder or different dose timing could help.
Sticky, tar-like, foul-smelling stools, especially with weakness, can mean blood from higher in the gut. Report any stool that looks like tar or has red blood.
C. Diff and Other Infections
C. difficile (C. diff) is a bacterium that takes over the gut after antibiotics, and it is the most common cause of diarrhea picked up in hospitals.12PubMed. Clostridium difficile infection in dialysis patients People on hemodialysis are 2 to 2.5 times more likely to get it.13PubMed Central. Suggestions for the prevention of Clostridioides difficile spread within outpatient hemodialysis facilities One reason is antibiotics: about one-third of hemodialysis patients get IV antibiotics each year.14PubMed Central. Suggestions for the prevention of Clostridioides difficile spread within outpatient hemodialysis facilities The risk is highest in people 65 and older and those who have had a bloodstream infection.15PubMed. Clostridium difficile infection in dialysis patients
The gut normally holds many harmless bacteria that crowd out harmful ones. Antibiotics kill some of these helpful bacteria along with the target infection, leaving space for C. diff to multiply. The bacterium then releases toxins that inflame the bowel and cause watery diarrhea. Dialysis adds exposure on top of that: frequent clinic visits and hospital stays mean more contact with places that may carry C. diff spores, which survive on surfaces for a long time, so you don’t need contact with a sick person.
Suspect C. diff if you have three or more watery stools a day during or after antibiotics, or if diarrhea began in or soon after a hospital stay. Fever or cramps along with it strengthen the case. C. diff can start as mild diarrhea and belly pain and progress to fever.16PubMed Central. Clostridium difficile Peritonitis: An Emerging Infection in Peritoneal Dialysis Patients A stool test confirms it, so ask for one.
In peritoneal dialysis, gut bacteria can cross a damaged bowel wall into the belly, causing peritonitis.17PubMed Central. Clostridium difficile Peritonitis: An Emerging Infection in Peritoneal Dialysis Patients Diarrhea with belly pain and cloudy drained fluid is a warning combination.18PubMed Central. Clostridioides difficile associated peritonitis in peritoneal dialysis patients – a case series based review of an under-recognized entity with therapeutic challenges If you are on peritoneal dialysis and get diarrhea, report it, because infection can reach the belly lining.
To limit spread, wash with soap and water, which removes C. diff better than alcohol gel. Tell the unit so staff can take precautions, and clean the toilet at home with a bleach-based cleaner.
Less Common but Serious Causes
Diabetes is a leading cause of kidney failure, and it can cause diarrhea in its own right. Up to 20% of people with diabetic gut nerve damage get diarrhea, often at night.19PubMed Central. A Practical Approach to Gastrointestinal Complications of Diabetes It shows up mostly when blood sugar is poorly controlled and nerve damage is present elsewhere.20PubMed Central. A Practical Approach to Gastrointestinal Complications of Diabetes
Years of high blood sugar can injure the nerves that control how the bowel moves. Diarrhea that wakes you from sleep is less typical of simple dietary upset, and in someone with diabetes it may point toward nerve damage, though it can have other causes. Mention the night pattern to your team, since it changes which tests and treatments make sense.
A rare but dangerous problem is loss of blood supply to the bowel without a blocked artery.21Elsevier / Journal of the American College of Surgeons. Nonocclusive mesenteric infarction in hemodialysis patients In one report, everyone affected had drops in blood pressure during hemodialysis in the week before belly symptoms.22Elsevier / Journal of the American College of Surgeons. Nonocclusive mesenteric infarction in hemodialysis patients Most also had high blood pressure, and many had diabetes or hardened arteries.23Elsevier / Journal of the American College of Surgeons. Nonocclusive mesenteric infarction in hemodialysis patients Reduced bowel blood flow is a recognized cause of bloody diarrhea in dialysis patients.24PubMed Central. Atypical cause of intractable diarrhea in a hemodialysis patient, masked by Clostridium difficile-associated diarrhea and ischemic colitis: a case report
After many years on hemodialysis, a protein called amyloid can build up in the bowel wall.25PubMed. Severe gastrointestinal complications of dialysis-related amyloidosis in two patients on long-term hemodialysis Amyloid in the bowel lining can cause diarrhea and poor absorption of food.26PubMed Central. Gastrointestinal amyloidosis: A focused review Signs that this is more than routine diarrhea include severe belly pain out of proportion to what you’d expect after a session with low blood pressure, blood in the stool, and weight loss over months.
Why Diarrhea Is Riskier When You’re on Dialysis
A fistula is the joined artery and vein in the arm used for hemodialysis. Severe diarrhea and dehydration have caused a fistula to clot suddenly, because the lost fluid lowered blood pressure and thickened the blood.27PubMed. Preventing embolus shedding from an arteriovenous fistula during hemodialysis treatment Severe dehydration also raises the risk of heart problems in dialysis patients.28PubMed Central. Health risk of travel for chronic kidney disease patients
The access is your lifeline for hemodialysis, and a clotted one can’t be used for treatment. Restoring it may need a procedure, and in the meantime you may need a temporary catheter, which carries infection risk.
During a bout of diarrhea, feel for the buzz over your access every day. A missing buzz is an emergency, so call the unit right away. Dizziness when you stand suggests fluid loss, and it helps to tell staff before the session so fluid removal can be adjusted.
Diarrhea can also lower potassium and change other blood levels, so your next blood tests may need to happen sooner. Weakness or palpitations warrant a call.
Safe Treatment and Fluids at Home
Loperamide (Imodium) needs no dose change for kidney failure because it leaves mainly through stool.29Food and Drug Administration. IMODIUM (loperamide hydrochloride) Capsules Still, one dialysis provider advises using it no more than 48 hours.30Fresenius Kidney Care. Managing over-the-counter medications with kidney disease It slows the bowel, which brings comfort, but it does not treat the cause. If loose stools continue past that limit, the cause needs to be found rather than masked. Follow the package dose unless your team says otherwise.
Avoid Pepto-Bismol and Kaopectate, which can harm the kidneys.31Fresenius Kidney Care. Managing over-the-counter medications with kidney disease Anti-diarrhea medicine can also make C. diff worse, so get tested first if C. diff is possible.
Diarrhea may mean you need more fluid than your usual limit.32National Kidney Foundation. The Dos and Don’ts of Fluid Management for Kidney Disease Call your care team for a temporary fluid target rather than guessing. Oral rehydration helps prevent dangerous dehydration,33PubMed Central. Health risk of travel for chronic kidney disease patients but many store-bought rehydration drinks contain potassium, so ask which to use. When you call, have these ready: how many stools and for how many days, any new medicine or recent antibiotic, any fever, blood or belly pain, and any weight change or dizziness.
While it settles, eat small bland meals within your kidney diet. Your dietitian can suggest low-potassium options. Avoid lots of sugar-free gum or candy, which can loosen stools.
Go to the hospital if your fistula has lost its buzz, if you have severe belly pain or blood, if your peritoneal fluid turns cloudy, or if you faint.
Travelling on Dialysis Without Getting Sick
Traveller’s diarrhea poses extra danger on hemodialysis because dehydration can block the access.34PubMed Central. Health risk of travel for chronic kidney disease patients Plan with your unit before you go.
Arrange treatments at a guest dialysis unit ahead of time, since spots can fill up and the unit may need your records. Ask your own unit for a summary of your treatment, medicines and recent blood results to carry with you. Save the guest unit’s number in your phone.
Where tap water is unsafe, drink bottled water, skip ice, and use bottled water for brushing teeth. Choose food that is cooked and served hot, and be careful with raw salads and unpeeled fruit. Wash your hands before eating.
Pack loperamide and remember the 48-hour limit. Ask your team for a kidney-safe rehydration plan before you leave.