Dialysis keeps people with kidney failure alive, but it is not a gentle process, and pretending otherwise does a disservice to the millions who depend on it. Every session forces rapid shifts in fluid, electrolytes, and blood pressure that ripple across the cardiovascular system, the brain, the immune system, the bones, and the gut. These effects accumulate over months and years. Understanding what dialysis actually does to your body is not a reason to refuse treatment; for most people it remains the best available option short of a transplant. But it is a reason to take the type of access you use, the frequency of sessions, and the broader management of your health seriously.
What Happens to Your Heart During a Session
The single biggest immediate stress of hemodialysis is on the heart. During each session, a machine pulls excess fluid from your blood through a process called ultrafiltration. Your body tries to refill the blood vessels by drawing fluid from surrounding tissues, but it often cannot keep pace with how fast fluid is being removed. The result is a temporary drop in blood volume, and frequently a drop in blood pressure.
That blood-pressure drop matters because it can starve parts of the heart muscle of adequate blood flow. Research has found that roughly two-thirds of hemodialysis patients experience what clinicians call myocardial stunning during a session, where segments of the heart temporarily stop contracting normally because of reduced blood supply. Age, the volume of fluid removed, episodes of low blood pressure during treatment, and markers of heart-muscle injury all independently predict whether stunning occurs.1PubMed Central. Hemodialysis-induced cardiac injury: determinants and associated outcomes Repeated stunning over hundreds of sessions can lead to lasting damage, contributing to the high rates of heart failure seen in long-term dialysis patients.
On top of the acute hemodynamic stress, kidney failure itself accelerates hardening and calcification of blood vessels. When your kidneys stop clearing phosphorus effectively, elevated phosphorus and other waste products can transform the smooth-muscle cells lining arteries into cells that resemble bone-forming cells, depositing calcium into the vessel walls.2PubMed. Pathophysiology of vascular calcification in chronic kidney disease Dialysis helps clear phosphorus but does not fully reverse this process, and some studies show that both medical therapy and surgery for the resulting hormonal imbalances can stabilize but not shrink existing calcification in the coronary arteries or heart valves.3PubMed. Parathyroidectomy versus oral cinacalcet on cardiovascular parameters in peritoneal dialysis patients with advanced secondary hyperparathyroidism (PROCEED): a randomized trial
Effects on the Brain and Thinking
The same blood-pressure swings that stun the heart can also starve the brain of adequate blood flow. Conventional hemodialysis may trigger repeated episodes of reduced blood supply to the brain, and over time these can chip away at cognitive function. Both obvious strokes and silent ones, small areas of damage that produce no immediate symptoms, appear to be far more common in dialysis patients than in the general population. One guidance document notes that strokes are up to nine times more frequent in people on dialysis, roughly doubling the risk of dementia.4Clinical Kidney Journal. Cognitive impairment in CKD patients: a guidance document by the CONNECT network
The pattern of cognitive decline in dialysis patients tends to show up in executive functions: planning, attention, mental flexibility, and multitasking. This tracks with the kind of damage seen in the brain’s white matter, the wiring that connects different regions. Hemodialysis patients often fare worse in cognitive testing than those on peritoneal dialysis, likely because the sharp hemodynamic swings of hemodialysis sessions are harder on the brain than the gentler, continuous fluid removal of peritoneal dialysis.5PubMed Central. Cognitive impairment in the aging dialysis and chronic kidney disease populations: an occult burden This does not mean every hemodialysis patient will develop dementia, but it underscores how cumulative the vascular stress can be.
Your Immune System Under Repeated Assault
Every time blood flows through the dialysis machine’s membrane, it meets a foreign surface, and the immune system reacts. The complement cascade, one of the body’s oldest defense systems, gets activated. This triggers a chain reaction: white blood cells called neutrophils are recruited to the area, inflammatory signaling molecules are released, and oxidative stress increases. The inflammatory messenger interleukin-8 ramps up during each session, promoting further neutrophil activity and the release of enzymes that damage surrounding tissue.6PubMed Central. A Critical Role of Neutrophil-Driven Amplification of Chronic Microinflammation in the Biocompatibility of Hemodialysis
Modern dialysis membranes are far more biocompatible than the cellulose-based ones that first raised alarms about immune activation back in the 1970s.7PubMed Central. The Janus-faced nature of complement in hemodialysis: interplay between complement, inflammation, and bioincompatibility unveiling a self-amplifying loop contributing to organ damage But even newer synthetic membranes still trigger complement activation and neutrophil responses, just to a lesser degree.8PubMed Central. Biocompatibility in hemodialysis: artificial membrane and human blood interactions Three times a week, year after year, this low-grade inflammatory hit accumulates. It contributes to the chronic inflammation that underlies so many of the other complications on this list, from cardiovascular disease to anemia to muscle wasting.
The Access Point Changes Your Risk
Hemodialysis requires a reliable way to move large volumes of blood in and out of the body. The three main options are an arteriovenous fistula (a surgically created connection between an artery and a vein, usually in the arm), a graft (an implanted tube bridging an artery and vein), and a central venous catheter (a tube placed in a large vein in the neck or chest). Which one you use changes your risk profile dramatically.
A large meta-analysis found that patients using catheters had about 50 percent higher risk of death from any cause and more than double the risk of fatal infections compared with those using fistulas.9PubMed Central. Associations between hemodialysis access type and clinical outcomes: a systematic review Catheter users also faced higher cardiovascular event rates. In a six-month follow-up study, 24 patients using permanent catheters developed infections while only one patient with a fistula did.10PubMed Central. Comparison of Complications of Arteriovenous Fistula with Permanent Catheter in Hemodialysis Patients: A Six-month Follow-up Among older patients starting hemodialysis, fistula use was associated with roughly 60 percent lower risk of bloodstream infection hospitalization compared with catheter or graft use.11Kidney Medicine. Vascular Access and Risk of Bloodstream Infection Among Older Incident Hemodialysis Patients
The practical implication is simple: if you know you are heading toward dialysis, getting a fistula created early enough for it to mature before your first session is one of the highest-impact things you can do. Not everyone’s blood vessels cooperate, and some people need grafts or catheters for anatomical or medical reasons. But the data on infection and mortality differences are stark enough that access planning should be a conversation well before dialysis starts.
Muscle Loss and Nutritional Drain
Each hemodialysis session pulls amino acids and small proteins across the membrane along with the waste products it is designed to remove. The loss of these building blocks, combined with lower food intake on dialysis days and the inflammatory hit described above, creates a hostile environment for maintaining muscle. Research from the International Society of Renal Nutrition and Metabolism details how protein breakdown increases during and for at least two hours after each session, while protein synthesis drops. The combination means a net loss of muscle protein with every treatment.12Journal of Renal Nutrition. Etiology of Protein-Energy Wasting in Chronic Kidney Disease: A Consensus Statement from the International Society of Renal Nutrition and Metabolism (ISRNM)
Over months and years, this protein-energy wasting contributes to frailty, weakness, and poor functional status. It also creates a frustrating dietary bind: you need to eat more protein to counteract the losses, but kidney failure limits how much phosphorus and potassium you can safely consume, and many high-protein foods are rich in both. Working with a renal dietitian to thread that needle is not optional, it is essential for preserving muscle mass and energy levels.
Anemia and Erythropoietin Resistance
Healthy kidneys produce erythropoietin, the hormone that tells bone marrow to make red blood cells. When kidneys fail, erythropoietin production plummets, and most dialysis patients develop anemia. Synthetic erythropoietin injections are the standard treatment, but a significant number of patients do not respond adequately. The most common reason is iron deficiency, but even after correcting iron levels, many patients remain resistant. Inflammation, infection, poor nutrition, inadequate dialysis, and hormonal imbalances from disordered bone metabolism all play a role.13PubMed Central. Resistance of dialyzed patients to erythropoietin
This resistance is not just a lab curiosity. Patients who respond poorly to erythropoietin face more hospitalizations, higher mortality, and a greater need for blood transfusions. In some patients with iron overload, where giving more iron could be harmful, intravenous vitamin C has been used to help mobilize trapped iron stores and restore some responsiveness to erythropoietin therapy.14Nephrology Dialysis Transplantation. Resistance to erythropoietin in iron-overloaded haemodialysis patients can be overcome by ascorbic acid administration Chronic anemia compounds the fatigue, exercise intolerance, and cognitive fog that dialysis patients already struggle with.
Fatigue, Depression, and the Recovery Burden
Ask anyone on hemodialysis what they dread most and a large number will say the exhaustion that follows each session. Post-dialysis fatigue can last hours or stretch through the rest of the day, eating into work, family time, and any sense of normalcy. Researchers have proposed several explanations, including the inflammatory response, fluid and electrolyte shifts, and disruption of the body’s stress-hormone axis, but no single mechanism has been pinned down with strong evidence.15PubMed Central. Fatigue in Patients Receiving Maintenance Hemodialysis: A Review That uncertainty makes it hard to treat directly, and most current approaches focus on managing contributing factors like anemia, poor sleep, and depression.
Mental health takes a serious hit. Studies report widely varying depression rates among hemodialysis patients depending on the screening tools used, but the numbers are consistently high. One study found that close to half of hemodialysis patients screened positive for depression, about 60 percent for insomnia, and roughly a quarter for elevated sleep apnea risk. Even the caregivers were affected, with about a third showing signs of depression.16PubMed Central. Depression, insomnia and sleep apnea in patients on maintenance hemodialysis Other studies using different thresholds report lower depression rates, but even the more conservative estimates show that dialysis patients carry a substantially higher burden of mood disorders and sleep problems than the general population.17Applied Nursing Research. Depression, sleep disturbance, and quality of life in patients undergoing dialysis therapy The relentless schedule, dietary restrictions, fluid limits, and physical discomfort of dialysis create a quality-of-life squeeze that deserves more attention than it typically gets.
Joint and Bone Complications Over the Long Haul
A complication unique to long-term dialysis is the buildup of a protein called beta-2 microglobulin. Healthy kidneys clear this protein, but dialysis membranes, especially older ones, do not remove it efficiently. Over years, beta-2 microglobulin accumulates and folds into amyloid deposits that settle in joints, tendons, and bones. The resulting condition, dialysis-related amyloidosis, was first described nearly half a century ago and remains a concern for anyone on dialysis for many years.18PubMed Central. Beta-2 Microglobulin Amyloidosis: Past, Present, and Future
The clinical picture includes painful and swollen joints in the shoulders, wrists, and hips; carpal tunnel syndrome from amyloid deposits pressing on wrist nerves; and bone cysts that weaken the skeleton. A survey of 95 long-term hemodialysis patients identified at least three distinct patterns of joint disease linked to beta-2 microglobulin amyloid deposition.19PubMed Central. ‘Dialysis related arthropathy’: a survey of 95 patients receiving chronic haemodialysis with special reference to beta 2 microglobulin related amyloidosis Switching to more modern, high-flux membranes has been shown to improve symptoms, and the incidence of severe amyloidosis has fallen as membrane technology has improved.20PubMed. Dialysis-related beta 2 microglobulin-amyloid arthropathy. Improvement of clinical symptoms after a switch of dialysis membranes But the risk has not disappeared, particularly for patients who spend a decade or more on dialysis before transplant or for those who never receive one.
The Gut Connection
Kidney failure reshapes the community of bacteria living in your intestine. As waste products build up in the blood, they alter the gut environment, favoring bacteria that produce additional toxins, including indoxyl sulfate and p-cresyl sulfate. These protein-bound toxins are poorly removed by standard dialysis because they cling to blood proteins and cannot cross the membrane easily. Meanwhile, the intestinal lining itself becomes more permeable, allowing bacterial toxins to leak into the bloodstream, which adds to oxidative stress and damages the kidneys, cardiovascular system, and endocrine organs.21PubMed Central. The Impact of CKD on Uremic Toxins and Gut Microbiota
This creates a feedback loop. The sicker the kidneys, the more disrupted the gut; the more disrupted the gut, the more toxins enter the blood; and standard dialysis cannot fully clear those particular toxins. Research into targeted removal of protein-bound uremic toxins and strategies to restore a healthier gut microbiome are active areas of investigation, but for now this remains one of dialysis’s significant limitations.
Peritoneal Dialysis and Preserving What Your Kidneys Still Do
Not all dialysis is the same. Peritoneal dialysis uses the lining of your abdomen as the filter, with fluid exchanges happening at home throughout the day or overnight. Because it removes fluid and waste more gradually, it tends to cause less hemodynamic stress than conventional hemodialysis. One of its notable advantages is that it appears to preserve residual kidney function longer. Even a small amount of remaining kidney function provides benefits that go well beyond waste clearance: better blood pressure and fluid control, improved nutritional status, lower rates of peritonitis, continued production of natural erythropoietin and vitamin D, and better clearance of the medium-sized toxins that dialysis membranes struggle with.22PubMed Central. A Review of Residual Kidney Function in Peritoneal Dialysis Patients
Peritoneal dialysis is not without its own risks, including peritonitis from infected fluid exchanges and eventual loss of the peritoneal membrane’s filtering ability over years. But for many patients, particularly those who value independence and want to avoid the hemodynamic battering of thrice-weekly hemodialysis, it is worth discussing with their care team early in the process rather than as a fallback.
Dialysis Versus Conservative Care in Older Adults
For younger and relatively healthy patients, the survival advantage of dialysis over no dialysis is clear. A systematic review and meta-analysis found that overall, dialysis is associated with roughly half the mortality risk compared with conservative care, with longer median survival from the time the treatment decision is made.23PubMed Central. Survival of patients who opt for dialysis versus conservative care: a systematic review and meta-analysis In one study, patients choosing dialysis had a one-year survival rate near 90 percent and a median survival of about 53 months, compared with 32 months for conservative-care patients who were considered suitable for dialysis but chose not to start it.24PubMed Central. Survival of Older Adults Choosing Dialysis or Conservative Kidney Management, Stratified by Suitability for Dialysis
The picture shifts, however, for older adults with significant frailty or multiple other serious health conditions. In that group, the survival advantage of dialysis narrows. Conservative kidney management provided comparable or sometimes better quality of life, was associated with fewer hospitalizations, and patients managed conservatively were more likely to die at home, which aligned more closely with many people’s end-of-life preferences.25PubMed Central. Dialysis versus conservative kidney management in older adults: why one size does not fit all For someone in their eighties with multiple organ problems and limited functional independence, spending three days a week in a dialysis chair may add a few months of life while subtracting considerably from its quality. That trade-off deserves an honest conversation, not a default assumption that everyone should start dialysis.
Incremental Starts and Gentler Approaches
The standard hemodialysis prescription in most countries is three sessions per week from day one. But there is growing interest in incremental dialysis, where patients start with just one or two sessions per week and increase frequency only as their remaining kidney function declines further. The rationale is straightforward: if your kidneys are still doing some of the work, why expose yourself to the full physiological toll of thrice-weekly treatment before you need to? Incremental hemodialysis softens the initial shock of starting therapy and may help preserve residual kidney function longer, which carries all of the downstream benefits discussed earlier.26PubMed. The ABCs of personalized incremental dialysis start, Le Mans style
This approach is more established in peritoneal dialysis, where incremental starts have been common practice for years, but it is gaining traction in hemodialysis as well. It requires careful monitoring of kidney function and waste levels to ensure you are still getting adequate clearance. Not every dialysis center offers it, and the entrenched three-times-a-week schedule has strong institutional momentum. But for patients with meaningful residual kidney function at the start of dialysis, asking about an incremental approach is reasonable.
How Dialysis Affects Children Differently
Children on maintenance hemodialysis face all of the complications that adults do, plus a set of problems unique to growing bodies. Loss of kidney function disrupts the balance of calcium and phosphorus needed for bone development, causes anemia, and frequently leads to growth delay and delayed puberty.27PubMed Central. Endocrine and Growth Abnormalities in Children with Kidney Failure on Maintenance Hemodialysis – Experience of a Single Center from Western Romania Growth hormone therapy can help, but the response in children on dialysis is significantly weaker than in children with earlier stages of kidney disease, likely because the body becomes more resistant to growth hormone’s effects as kidney function worsens. Intensifying dialysis with daily treatments has been shown to markedly improve the response to growth hormone, suggesting that the adequacy of dialysis directly affects whether a child can catch up in height.28Nature Reviews Nephrology. Clinical practice recommendations for growth hormone treatment in children with chronic kidney disease
For pediatric patients, the stakes are different in another way: most children on dialysis are waiting for a kidney transplant, and dialysis is a bridge meant to be temporary. The goal is to minimize cumulative damage to the heart, brain, bones, and growth trajectory during that waiting period. The complications are not theoretical future concerns but active threats to development happening in real time.