When kidneys stop working properly, haemodialysis becomes a lifeline—a treatment that takes over the crucial job of cleaning your blood when your own organs can no longer manage the task.

What Is Haemodialysis?

Haemodialysis is a medical treatment designed to filter waste products, excess fluids, and toxins from your blood when your kidneys are no longer able to perform this essential function on their own. Think of it as an artificial way to do what healthy kidneys normally do around the clock—keeping your blood clean and your body’s chemistry in proper balance. The treatment uses a special machine and a device called a dialyzer, sometimes referred to as an artificial kidney, to accomplish this filtering process outside of your body.^[1]

During a haemodialysis session, blood is removed from your body through soft tubes connected to needles placed in your arm. This blood travels through the dialyzer, which contains thousands of very thin, hollow fibers. As your blood passes through these fibers, a specially prepared fluid called dialysate flows in the opposite direction on the outside of the fibers. Waste products, extra salt, and excess water from your blood move across the fiber walls into the dialysate solution. The cleaned blood then returns to your body through another tube. Throughout this process, the dialysis machine carefully monitors your blood pressure and controls how quickly blood flows through the system to ensure your safety.^[1]

The dialysate is carefully formulated with water and specific chemicals chosen by your nephrologist—a doctor who specializes in kidney problems. The balance of these chemicals can be adjusted to meet your individual needs, helping to safely remove wastes while maintaining proper levels of important minerals like potassium, sodium, and calcium in your blood. This precise control is what makes haemodialysis effective at preventing dangerous buildups of toxins that could otherwise be life-threatening.^[1]

Who Needs Haemodialysis?

Haemodialysis becomes necessary when someone develops severe kidney disease. Your kidneys perform the vital job of filtering your blood, removing waste products and extra fluid, and sending this waste out of your body in urine. When kidneys can no longer do this work adequately, dangerous substances begin to accumulate in your bloodstream, creating a serious medical condition known as kidney failure.^[3]

Most people require haemodialysis when they reach late-stage kidney disease or end-stage kidney disease (ESKD), also called end-stage renal disease (ESRD). Your doctor will typically recommend starting dialysis when your kidneys are functioning at only 10 to 15 percent of their normal capacity. This determination is made using a measurement called estimated glomerular filtration rate (eGFR), which is calculated from blood test results along with factors like your age and sex. A normal eGFR is much higher, and when it drops to very low levels, the kidneys can no longer support your body’s needs on their own.^[5]

Sometimes kidney failure happens suddenly rather than gradually. This is called acute kidney injury and can result from severe illness or injury. In these cases, haemodialysis may be needed temporarily while the kidneys recover. However, for most people with chronic kidney disease that has progressed to ESRD, dialysis becomes a long-term or permanent necessity unless they receive a kidney transplant. You might also need haemodialysis while waiting for a kidney transplant to become available.^[3]

The decision about when to start haemodialysis takes into account several factors beyond just your kidney function numbers. Your doctor will consider your overall health, any symptoms you’re experiencing (such as nausea, vomiting, swelling, or fatigue caused by waste buildup), your quality of life, and your personal preferences. This makes it a collaborative decision between you and your healthcare team.^[5]

Epidemiology: How Common Is Haemodialysis?

Haemodialysis is the most frequently used type of dialysis worldwide. About 90 percent of all people who need dialysis treatment receive haemodialysis rather than other forms of kidney replacement therapy. This makes it by far the dominant approach to managing kidney failure in clinical practice.^[3]

Globally, approximately 2.5 million people were receiving chronic renal replacement therapy in 2010, which includes haemodialysis, other forms of dialysis, and kidney transplantation. The need for these treatments continues to rise around the world, creating an increasing burden on healthcare systems. The growing number of people requiring dialysis reflects the rising prevalence of conditions that damage the kidneys over time.^[6]

Causes: Why Do Kidneys Fail?

Understanding why kidneys fail helps explain why so many people eventually need haemodialysis. The two main culprits responsible for end-stage renal disease are diabetes mellitus and high blood pressure (hypertension). Diabetes accounts for about 45 percent of all cases of kidney failure requiring dialysis, while hypertension is responsible for approximately 30 percent. Together, these two conditions cause the majority of kidney disease that progresses to the point where dialysis becomes necessary.^[6]

Diabetes damages the kidneys gradually over many years. High blood sugar levels harm the tiny blood vessels in the kidneys that do the filtering work. Over time, this damage accumulates and the kidneys lose their ability to clean the blood effectively. Similarly, high blood pressure puts excessive strain on the blood vessels in the kidneys, eventually causing them to weaken and lose function. Both conditions illustrate how kidney failure is often the result of years of damage rather than a sudden event.^[6]

Several other diseases and conditions can also damage kidneys and lead to the need for haemodialysis. These include lupus, certain inherited kidney diseases, chronic infections, and various other medical problems. In some cases, people develop kidney failure for reasons that doctors cannot fully identify. Regardless of the underlying cause, once the kidneys have lost most of their function, the body can no longer maintain proper balance without help from treatments like haemodialysis.^[10]

Types of Haemodialysis

Not all haemodialysis is the same. There are two main types, and understanding the difference can help you and your doctor decide what approach might work best for your situation and lifestyle.^[3]

In-center haemodialysis is the most traditional form of this treatment. With this approach, you travel to a special healthcare facility—either a dedicated dialysis clinic or a dialysis unit within a hospital—for your treatments. At the center, trained dialysis nurses or technicians perform the procedure for you. They handle all the technical aspects, including placing the needles, operating the machine, and monitoring you throughout the session. Most people receiving in-center haemodialysis go to the facility three times per week, with each session lasting between three and four hours. Some larger patients may need longer sessions, occasionally up to five hours. After treatment, many people feel tired for several hours, which is a normal response to the process.^[3]

Home haemodialysis offers more flexibility and independence for those who are willing and able to learn the procedure. With this option, treatments take place in your own home using equipment that is provided to you—you don’t have to purchase a machine yourself, as Medicare or health insurance typically covers the cost. Before you can start home dialysis, you need to undergo training that usually takes several weeks to a few months. During this training period, healthcare professionals teach you (and possibly a helper or caregiver) how to operate the equipment, place the needles into your access site, monitor the machine and your blood pressure during treatment, keep proper records, and handle any common problems that might arise.^[3]

Home haemodialysis offers three different scheduling options. Conventional home haemodialysis follows a similar pattern to in-center treatment, with sessions three times per week lasting three to four hours each. Short daily home haemodialysis uses newer technology that allows for shorter treatment times—about two hours per session—but performed more frequently, typically five to seven days per week. Nocturnal (overnight) home haemodialysis is done while you sleep, with treatments lasting six to eight hours and performed four to six nights per week. This last option provides more total hours of dialysis each week, which can be beneficial for removing more waste from your blood.^[3]

Home haemodialysis has several advantages. Because treatments happen more frequently and proceed more slowly, they tend to be gentler on your body. Many people find that home dialysis helps keep their blood pressure lower, sometimes eliminating the need for blood pressure medications. It may do a better job of removing waste products, be easier on your heart, and cause fewer unpleasant symptoms like nausea, headaches, cramps, itching, and tiredness. Perhaps most importantly, home dialysis allows you to fit treatments into your own schedule rather than arranging your life around clinic appointments.^[11]

However, home haemodialysis isn’t right for everyone. It requires significant responsibility and commitment. You need to be capable of learning the procedures and comfortable handling your own medical care, or have a caregiver willing to help. Not all dialysis centers offer home dialysis programs, which can limit access to this option. Some people simply prefer the structure and professional oversight of in-center treatment. The choice between in-center and home haemodialysis is highly personal and should be made in consultation with your nephrologist and healthcare team.^[11]

Preparing for Haemodialysis

Starting haemodialysis requires advance preparation, sometimes beginning weeks or even months before your first treatment. The most important preparatory step is creating what’s called vascular access—a way for blood to be safely removed from and returned to your body during each dialysis session.^[3]

Before you begin haemodialysis treatments, a surgeon will need to enlarge some of your blood vessels to make dialysis access easier and allow blood to flow in and out of your body fast enough for effective treatment. This surgical procedure is typically performed on your arm. The access site is where needles will be placed at the start of each dialysis session. These needles connect to the soft tubes that carry blood to and from the dialysis machine.^[10]

If placing needles bothers you, you can request a numbing cream or spray to reduce discomfort. Many people who do home dialysis eventually learn to place the needles themselves after receiving proper training from their healthcare team, which can give them a greater sense of control over their treatment.^[1]

Life on Haemodialysis: What to Expect

Living with haemodialysis means making significant adjustments to your daily routine, but many people find ways to maintain active, fulfilling lives despite the demands of treatment. Understanding what to expect can help you prepare mentally and practically for this major life change.^[5]

One of the first adjustments involves your treatment schedule. If you’re receiving in-center haemodialysis, you’ll need to arrange your work, family commitments, and social activities around your dialysis appointments. Three times per week, you’ll spend several hours at the dialysis center, plus travel time. This can feel restrictive at first, but many people develop routines that help them cope. Some use dialysis time to read, watch videos, work on hobbies, or simply rest.^[1]

Following a strict dialysis diet is another essential adjustment. What you eat and drink matters significantly when your kidneys aren’t working properly. You’ll need to be careful about your intake of certain nutrients like potassium, phosphorus, and sodium, as these can build up to dangerous levels between dialysis sessions. Fluid intake often needs to be limited as well, since your damaged kidneys can’t remove excess water effectively. Working with a dietitian who specializes in kidney disease can help you learn to make food choices that keep you healthy while still enjoying meals.^[5]

Medications become an important part of your daily routine on haemodialysis. Many people on dialysis take several different medications, and the timing matters. You’ll need to work closely with your healthcare team to understand what each medication does, when to take it, and why it’s necessary. Staying organized with a medication schedule or pill organizer can help ensure you don’t miss doses.^[5]

Physical and emotional changes are also part of the experience. It’s common to feel tired for several hours after a dialysis session. Some people experience other symptoms like nausea, headaches, muscle cramps, or itching. These side effects can often be managed with adjustments to your treatment or medications. Emotionally, adjusting to life with a chronic condition and the dependence on dialysis can be challenging. Many people benefit from support groups where they can connect with others who understand what they’re going through.^[5]

How Haemodialysis Works: The Technical Process

Understanding the mechanics of haemodialysis can help demystify the treatment and ease anxiety about what happens to your blood during each session. The process is carefully controlled and monitored to ensure safety and effectiveness.^[1]

At the beginning of each treatment, the dialysis nurse or technician (or you, if you’re doing home dialysis) places two needles into your vascular access site. One needle draws blood out of your body, while the other returns cleaned blood back to you. The blood travels through soft, flexible tubes connected to the dialysis machine.^[1]

The heart of the system is the dialyzer, which serves as an artificial kidney. Inside this device are thousands of very thin, hollow fibers—imagine them like tiny straws bundled together. Your blood flows through the inside of these hollow fibers. At the same time, the dialysate solution flows in the opposite direction on the outside of the fibers. This counter-current flow is intentional and increases the efficiency of waste removal.^[1]

The walls of these tiny hollow fibers are semi-permeable, meaning they allow certain substances to pass through while blocking others. Waste products, excess salt, and extra water in your blood can cross through the fiber walls into the dialysate. However, important blood cells and proteins are too large to pass through, so they remain safely in your bloodstream. The filtered blood continues through the hollow fibers and eventually returns to your body. Meanwhile, the dialysate carrying away your wastes is disposed of by the machine.^[1]

Throughout the entire process, the dialysis machine acts as a sophisticated monitoring and control system. It checks your blood pressure regularly and adjusts how quickly blood flows through the filter. It also controls the precise rate at which fluid is removed from your body. These continuous adjustments help ensure the treatment is both safe and effective, reducing the risk of complications like sudden drops in blood pressure.^[1]

Benefits of Haemodialysis

Haemodialysis performs several critical functions that your failing kidneys can no longer accomplish on their own. Understanding these benefits helps illustrate why this treatment is so vital for people with kidney failure.^[11]

The most fundamental benefit is the removal of dangerous waste products from your blood. When your kidneys fail, substances like urea (nitrogen waste from protein breakdown) and creatinine (muscle waste) accumulate in your bloodstream. These toxins can make you feel extremely ill and, if left unchecked, can be fatal. Haemodialysis efficiently removes these wastes, helping you feel better and preventing the serious complications of uremia.^[3]

Haemodialysis also removes excess salt and water that your body can no longer eliminate through urine. Without this removal, fluid would build up in your tissues, causing swelling (edema) in your legs, ankles, and other parts of your body. Fluid can even accumulate around your lungs and heart, making it difficult to breathe and potentially leading to heart failure. By removing this excess fluid, dialysis helps prevent these dangerous complications.^[11]

Another crucial function is maintaining safe levels of important minerals in your blood. Potassium, sodium, and calcium all need to be kept within narrow ranges for your body to function properly. Too much or too little of these minerals can cause serious problems, including dangerous heart rhythms. Haemodialysis helps keep these minerals balanced, protecting your heart and other vital organs.^[1]

Blood pressure control is another significant benefit. Kidney failure often causes high blood pressure, which can damage your heart and blood vessels. Haemodialysis helps control blood pressure both by removing excess fluid and by maintaining proper mineral balance. Many people find their blood pressure becomes easier to manage once they start regular dialysis treatments.^[11]

Finally, haemodialysis can help your body produce red blood cells more effectively. Healthy kidneys produce a hormone called erythropoietin that stimulates red blood cell production. When kidneys fail, anemia (low red blood cell count) is common. While haemodialysis doesn’t directly produce this hormone, the overall improvement in your body’s chemistry and the medications often given alongside dialysis can help address anemia.^[11]