Hemodialysis

Introduction

Starting hemodialysis is a major step in the care of advanced kidney disease. Whether dialysis has been planned for months as your kidney function slowly declined, or whether it began urgently in hospital, you are now entering a phase of treatment that will shape your weeks — the sessions themselves, the recovery between them, the food and fluid choices, the medications, and the ongoing conversations with your kidney team.

Hemodialysis does not cure kidney disease. What it does is take over many of the jobs your kidneys can no longer do well enough on their own — clearing waste products, removing extra fluid, and keeping the salts and acids in your blood in balance. With good care, many people live for years, and some for decades, on hemodialysis, continuing to work, raise families, travel, and pursue what matters to them.

This guide explains what hemodialysis is, how it fits among other treatments for kidney failure, what to expect at each stage, how to look after your access, what diet and fluid limits mean in practice, and what to watch for in the long term. It is written for adults preparing to start hemodialysis, those already on treatment, and family members supporting them.

What Is Hemodialysis?

Hemodialysis is a treatment in which your blood is passed through a machine that removes waste products and extra fluid, then returned to your body. The machine is sometimes called a dialysis machine, and the filter at the heart of it is called a dialyzer or “artificial kidney.”

Inside the dialyzer, your blood flows on one side of a thin membrane and a special fluid called dialysate flows on the other. Waste products such as urea and creatinine, and extra substances such as potassium, move from the blood across the membrane into the dialysate, which is then discarded. Extra water in the blood is also drawn out by carefully controlled pressure. Cleaned blood is returned to you continuously throughout the session.

Most people on long-term hemodialysis have three sessions a week, each lasting around four hours, though some treatment patterns are shorter and more frequent, and some are longer and slower. Sessions take place in one of three settings:

• In-centre hemodialysis — at a dialysis unit, staffed by nurses and technicians, supervised by a nephrologist. This is the most common pattern worldwide.
• In-hospital hemodialysis — for people who are acutely unwell, in intensive care, or in the early days after starting treatment.
• Home hemodialysis — for selected patients who, with a trained care partner, learn to run their own sessions at home. This typically allows more frequent, gentler treatment.

Hemodialysis is one of several ways to replace lost kidney function. The other main options are peritoneal dialysis (which uses the lining of the abdomen as the filter) and kidney transplantation. For some people, hemodialysis is short-term — a bridge until the kidneys recover from an acute injury or until a transplant becomes possible. For others, it is a long-term, life-sustaining therapy.

Who Needs Hemodialysis?

Hemodialysis is considered when your kidneys can no longer keep your body in safe balance. This may happen in two broad situations.

End-stage chronic kidney disease

Most people who start long-term hemodialysis have chronic kidney disease (CKD) that has progressed to its most advanced stage, sometimes called end-stage kidney disease or stage 5 CKD. The most common underlying causes are:

• Long-standing diabetes
• Long-standing high blood pressure
• Glomerulonephritis (inflammation of the kidney’s filtering units)
• Polycystic kidney disease and other inherited conditions
• Obstructive kidney disease and recurrent severe kidney infections

Severe acute kidney injury

In acute kidney injury (AKI), the kidneys lose function suddenly — often during a severe illness, after major surgery, or because of certain medications or toxins. When AKI is severe and not improving fast enough, short-term hemodialysis (or a closely related continuous treatment in intensive care) supports the body until the kidneys recover. In many of these cases dialysis can later be stopped.

How the decision is made

The decision to start hemodialysis is not based on a single number. Your nephrologist considers your symptoms, your laboratory results, how much fluid your body is holding, and how well other treatments are working. Common signs that pushed the decision to start include:

• Persistent tiredness, poor appetite, nausea, or vomiting linked to waste build-up (uraemia)
• Swelling and breathlessness from fluid overload that medication can no longer control
• Dangerously high potassium or severe acid build-up in the blood
• A very low estimated glomerular filtration rate (eGFR), usually combined with symptoms

International nephrology guidelines (KDIGO) emphasise starting dialysis based on symptoms and clinical condition rather than a fixed eGFR threshold. Two people with the same kidney numbers may start at different times depending on how they feel and what other illnesses they have.

Alternatives and Choices Before Starting

Before hemodialysis becomes the path forward, your kidney team will usually discuss the full range of options for end-stage kidney disease. Even after starting hemodialysis, some of these options remain open and worth understanding.

Peritoneal dialysis

Peritoneal dialysis (PD) uses the lining of your abdomen (the peritoneum) as a natural filter. Dialysis fluid is run into the abdomen through a soft catheter, left for several hours to absorb waste, and then drained. PD is done daily at home, either by manual exchanges during the day or by a small machine overnight. It avoids needles in the arm and the trip to a dialysis centre. Whether PD or hemodialysis suits an individual better depends on lifestyle, home setup, abdominal anatomy, and other medical factors.

Kidney transplantation

A kidney transplant offers the best long-term function and quality of life for many people with end-stage kidney disease. It is not suitable for everyone, and not everyone has a donor. Transplant evaluation can begin before dialysis starts (pre-emptive transplant) or while on dialysis. Hemodialysis is often a bridge to transplant.

Conservative kidney management

For some people — particularly those who are very frail, have many other serious illnesses, or for whom dialysis is unlikely to add good-quality time — a conservative care pathway focuses on symptom control, medication adjustment, diet, and supportive care without dialysis. This is a legitimate, well-recognised choice and is discussed openly by nephrology teams when relevant.

Which path fits any one person is a clinical decision made together with the kidney team, taking into account medical findings, personal values, and home circumstances.

The Hemodialysis Process: Step by Step

Hemodialysis is not a single event but an ongoing process. Below is a walk-through of the main stages.

Step 1: Creating dialysis access

• Arteriovenous (AV) fistula. A small operation joins an artery and a vein, usually in the arm. Over weeks to months the vein grows thicker and stronger so it can be needled for dialysis. KDOQI and KDIGO guidance describe AV fistulas as the preferred long-term access for most people because of lower infection and clotting rates and longer survival of the access itself.
• AV graft. A soft plastic tube is placed under the skin to join an artery and a vein. Grafts are used when the patient’s own veins are not suitable for a fistula. They can usually be used sooner than a fistula but have a higher risk of clotting and infection.
• Central venous catheter. A soft tube placed into a large vein in the neck or chest. Catheters can be used immediately, which is why they are common when dialysis must start urgently. Because they carry a higher risk of infection and other complications, they are generally seen as a short-term option while a fistula or graft is being prepared.

If you have advance warning that you will need dialysis, your team may refer you for fistula creation months ahead so that it is ready when needed.

Step 2: Education and dry weight assessment

Before regular sessions begin, you will spend time with nurses, dietitians, and sometimes social workers. They will explain how the machine works, how to care for your access, what to eat and drink, what your medications do, and what symptoms to report. The team will also work out your “dry weight” or target weight — the weight at which you are not carrying extra fluid. Hitting this weight at the end of sessions is one of the most important goals of treatment.

Step 3: Connecting to the machine

At each session, staff check your weight, blood pressure, pulse, and temperature, and inspect your access. If you have a fistula or graft, two needles are placed: one to draw blood out, the other to return it. With a catheter, the two lines are simply connected. Blood-thinning medication (usually heparin) is given to stop the blood clotting in the circuit.

Step 4: Filtration

Your blood is pumped slowly and continuously through the dialyzer. Inside, waste products move across the membrane into the dialysate. Extra fluid is removed by gentle pressure — this is called ultrafiltration. The machine constantly monitors flow, pressure, and other safety alarms.

During the session you can usually read, sleep, watch a screen, eat a light snack, or talk with neighbours. Some people feel cold and use a blanket; others feel sleepy.

Step 5: Ending the session

Toward the end, the blood remaining in the circuit is returned to you. Needles are removed and pressure is held over the sites until bleeding stops. Your weight, blood pressure, and access site are checked before you leave. You may feel washed out for an hour or two afterwards — this is normal and often improves as your body adjusts.

Step 6: The days between sessions

Hemodialysis works in pulses, not continuously like natural kidneys. Between sessions, waste products and fluid build up again. This is why fluid and dietary limits matter so much, and why missing or shortening sessions is risky — especially the longer gap (often the weekend), which is the period of highest cardiovascular risk for people on three-times-weekly schedules.

Step 7: Ongoing review

Every month or so, blood tests check how well dialysis is clearing wastes (a measure called Kt/V or URR), how your haemoglobin, calcium, phosphate, and other levels are doing, and how your nutrition is holding up. Your nephrologist adjusts the prescription — dialysis time, blood flow, dialysate composition, target weight, medications — based on these results and how you feel.

Settings and Schedules

Hemodialysis can be delivered in several patterns, and the right pattern depends on your medical needs and life circumstances.

Conventional in-centre hemodialysis

Three sessions a week, roughly four hours each, at a dialysis unit. This is the most widely available pattern and the one most people start on.

Home hemodialysis

Patients (with a trained care partner) run their own sessions at home, often more frequently — sometimes five or six shorter sessions a week, or longer overnight sessions. More frequent dialysis usually means fewer dietary and fluid restrictions, better blood pressure control, and less “washed-out” feeling. Home dialysis requires training over several weeks, suitable space at home, and a stable support situation.

Nocturnal hemodialysis

Long, slow sessions done overnight, either in a unit or at home. The gentler removal of fluid and waste over many hours is easier on the heart and often allows more freedom with diet.

The pattern that suits you is a discussion between you and your kidney team, taking into account your medical condition, vascular access, home situation, and preferences.

Diet, Fluids, and Medications

What you eat, drink, and take between sessions has a direct effect on how you feel during and after dialysis.

Fluid

Between sessions, your body holds on to fluid because urine output is usually reduced or absent. Too much fluid leads to swelling, breathlessness, high blood pressure, strain on the heart, and uncomfortable, sometimes dangerous, removal at the next session. Your team will give you a personal daily fluid allowance, usually based on how much urine you still pass plus a fixed amount. Strategies that help include sipping rather than gulping, sucking ice chips, using smaller cups, treating dry mouth with sugar-free chewing gum, and limiting salty foods that drive thirst.

Salt (sodium)

Lower salt intake reduces thirst, helps blood pressure, and makes fluid limits easier to keep. Most of the salt in a typical diet comes from processed foods, pickles, papads, sauces, packaged snacks, and restaurant meals rather than from the salt shaker.

Potassium

High potassium between sessions can cause dangerous heart rhythm problems. People on hemodialysis are usually advised to be cautious with high-potassium foods such as bananas, oranges, tomatoes, potatoes, coconut water, and many dried fruits. Soaking and double-boiling some vegetables can lower their potassium content. A renal dietitian will tailor advice to your test results.

Phosphorus

High phosphorus contributes to bone disease, itching, and calcium build-up in blood vessels. Phosphorus is high in dairy, nuts, lentils, dark colas, and many processed foods (where it is added as a preservative). Phosphate binders — medicines taken with meals — help reduce how much is absorbed.

Protein

Unlike earlier stages of CKD, where protein is often restricted, people on hemodialysis usually need a higher protein intake because the process itself removes some amino acids. Good-quality protein at each meal helps maintain muscle and immunity.

Common medications

• Phosphate binders taken with food
• Erythropoiesis-stimulating agents (often given as injections) and iron to treat anaemia of kidney disease
• Active vitamin D and sometimes calcimimetics for bone and parathyroid health
• Blood pressure medicines, adjusted around dialysis days
• Diabetes medications — doses often need to be reduced as kidney function falls and again on dialysis

Your vascular access is your lifeline. Protecting it is one of the most important things you can do.

For a fistula or graft:

• Check daily that you can feel the “thrill” (the buzzing vibration) over the access. Tell your team straight away if it changes, weakens, or disappears.
• Keep the area clean. Wash with soap and water before each dialysis session.
• Avoid tight sleeves, jewellery, or watches on that arm.
• Do not let anyone take blood, place a drip, or check blood pressure on that arm.
• Avoid sleeping on the access arm or carrying very heavy loads with it.
• Report redness, warmth, swelling, pain, or bleeding promptly.

For a catheter:

• Keep the dressing dry and intact. Do not get the area wet in baths or pools.
• Never open or handle the catheter at home unless trained to do so.
• Report fever, chills, redness, or discharge at the exit site immediately — catheter infections need urgent treatment.

Risks and Complications

Hemodialysis is generally safe, but as with any major treatment it has risks. Knowing them helps you and your team manage them early.

During or just after a session

• Low blood pressure — often from removing too much fluid too quickly. It can cause dizziness, nausea, cramps, or fainting.
• Muscle cramps, particularly in the legs.
• Nausea, headache, or feeling washed out after sessions.
• Bleeding from needle sites.
• Allergic reactions to parts of the circuit (uncommon).

Access-related

• Infection, especially with catheters
• Clotting (thrombosis) of a fistula or graft
• Narrowing (stenosis) of the access vessel
• Aneurysm formation in older fistulas
• “Steal” syndrome — reduced blood flow to the hand

Longer-term

• Cardiovascular disease. Heart problems are the leading cause of illness and death in people on dialysis. Blood pressure, fluid control, and management of cholesterol and diabetes are central to long-term care.
• Anaemia. Damaged kidneys produce less of the hormone that stimulates red blood cell production. Anaemia is managed with iron and erythropoiesis-stimulating agents.
• Bone and mineral disease. Disturbed calcium, phosphorus, vitamin D, and parathyroid hormone levels affect bones and blood vessels.
• Infections. People on dialysis are more vulnerable to infections generally, and to bloodstream infections from access in particular. Vaccinations (including hepatitis B, influenza, pneumococcus, and others as advised) are part of routine care.
• Nutrition problems from poor appetite or restrictive eating.
• Mental health. Depression and anxiety are common and treatable; raising them with the team is encouraged.

Hemodialysis in Children

Children can develop kidney failure from inherited conditions, congenital abnormalities of the urinary tract, glomerular diseases, or acute illness. Hemodialysis in children follows the same principles as in adults but with important differences:

• Care is delivered in paediatric dialysis units by teams trained in children’s kidney care, often together with paediatric nurses, dietitians, play specialists, and school liaison staff.
• Equipment and prescriptions are scaled to the child’s size; blood volume, ultrafiltration, and dialysate are carefully calculated to keep sessions safe.
• Vascular access in small children may rely more on central catheters; fistulas are created when veins are large enough.
• Growth, nutrition, schooling, and emotional development are central concerns. Growth hormone treatment is sometimes used. Nutritional support is more generous than in adult dialysis.
• Kidney transplantation is the preferred long-term treatment for most children with end-stage kidney disease, and hemodialysis is often a bridge to transplant.

Parents are closely involved in every aspect of care, including learning to recognise problems with access, fluid balance, and medications. Schools usually need to be informed and supported so the child can keep learning during this time.

Living with Hemodialysis

Work and study

Many people on hemodialysis continue to work or study. Evening or early-morning shifts at the dialysis unit, or home hemodialysis, can make this easier. Some people change to less physically demanding work. Talking openly with employers about a flexible schedule often helps.

Travel

Travel is possible with planning. Dialysis units in other cities or countries can host you for “holiday dialysis,” usually with several weeks’ notice and a transfer of medical records. Your kidney team can help organise this.

Emotional and mental health

Starting dialysis is a loss as well as a treatment — loss of kidney function, of a previous routine, of certainty about the future. Feelings of grief, anger, anxiety, or low mood are common and understandable. They are also treatable. Counselling, peer support groups, and, where appropriate, medication can all help. Family members also benefit from support.

Sexual health and fertility

Kidney failure and dialysis can affect libido, erectile function, menstrual cycles, and fertility. These changes are common but often unspoken. Raising them with your nephrologist opens the door to treatment options and to fertility advice when relevant.

Vaccinations and general health

Routine vaccinations recommended for people on dialysis, dental care, eye checks (especially for people with diabetes), and screening for other conditions should not be neglected. Your nephrologist and family doctor share the responsibility for this broader picture.

Long-term Outlook and Looking Ahead

Outcomes on hemodialysis vary widely. They depend on age, the underlying cause of kidney disease, heart and vessel health, nutrition, infection risk, and how consistently dialysis and medications are received. Many people live for years or decades on dialysis. Others, particularly those who are older or have several serious illnesses, may have shorter survival even with good dialysis. Honest conversations with your nephrologist about your individual outlook are appropriate at any stage.

For people who are suitable, kidney transplantation typically offers better long-term survival and quality of life than continuing on dialysis. Transplant assessment can be revisited over time as circumstances change. For others, continuing on well-run dialysis with attention to symptoms and quality of life is the right path. And for some, particularly later in the journey, a shift toward more comfort-focused care may become appropriate. None of these paths is a failure; they are different ways of caring for a long-term condition.

Frequently Asked Questions

Does hemodialysis hurt?

The treatment itself is not painful. Most people feel only the prick of the two needles at the start (with a fistula or graft); numbing cream or spray can be used. During the session you may feel cool, sleepy, or occasionally crampy or light-headed if blood pressure drops — tell the staff if you do.

How long will I be on dialysis?

It depends on the cause. In acute kidney injury, dialysis may be needed only for days or weeks until the kidneys recover. In end-stage chronic kidney disease, hemodialysis is usually long-term unless and until a kidney transplant becomes possible.

Can I still pass urine on dialysis?

Many people continue to pass some urine for months or years after starting dialysis, especially in the first year. This residual kidney function is valuable — it helps with fluid balance and overall well-being. Your team will factor it into your fluid allowance.

Why do I feel so tired after sessions?

Post-dialysis fatigue is common, particularly in the first weeks. It often reflects fluid shifts, blood pressure changes, and the body adjusting. Tell your team if it is severe or not improving — sometimes adjusting the prescription, the rate of fluid removal, or your dry weight helps.

Can I eat before or during a session?

Practice varies between units. Some allow light snacks during dialysis; others prefer you eat beforehand because eating during dialysis can lower blood pressure. Follow your unit’s guidance.

Can I exercise?

Yes. Regular, moderate exercise — walking, gentle strength work, stretching — helps the heart, mood, sleep, and muscle strength. Some units offer exercise during dialysis. Check with your team before starting a new programme, and avoid heavy lifting with the access arm.

Is it safe to miss or shorten a session?

Missing or cutting sessions short is one of the most consistent risks to health on dialysis. Waste and fluid build up quickly and can cause heart and breathing problems. If something genuinely prevents attendance, call your unit so a replacement session can be arranged.

Can I switch from hemodialysis to peritoneal dialysis, or the other way around?

Yes. Switching between dialysis types is possible and is sometimes the right move as circumstances change. It is a clinical decision discussed with your nephrologist.

Will I be eligible for a kidney transplant?

Many people on hemodialysis are eligible for transplant assessment. Eligibility depends on overall health, heart and vessel status, infection screening, and other factors. Ask your nephrologist about referral for evaluation; this can be done before or after starting dialysis.

Can I have home hemodialysis?

Home hemodialysis is suitable for selected patients with stable medical condition, suitable vascular access, a trained care partner, and an appropriate home setup. It involves several weeks of training. Not every unit offers a home programme; ask your team what is available.

Conclusion

Hemodialysis is a life-sustaining treatment that takes over essential work the kidneys can no longer do. It is demanding — in time, in lifestyle adjustments, and emotionally — but it is also enabling. With careful attention to vascular access, fluid and diet, medications, and the wider health picture, many people on hemodialysis live full, meaningful lives over many years.

Your kidney team — nephrologist, dialysis nurses, dietitian, and others — is your partner in this. Asking questions, raising symptoms early, keeping to your schedule, and looking after your access are the practical foundations of doing well. Whether hemodialysis turns out to be a bridge to transplant, a long-term home, or part of a broader plan that changes over time, it is one chapter in your kidney care story, not the whole of it.