Kidney failure happens when your kidneys lose enough function that they can no longer filter waste and excess fluid from your blood effectively. The two most common causes are diabetes and high blood pressure, which together account for the majority of cases. But medications, infections, genetic conditions, and sudden injuries can also destroy kidney tissue. Globally, about 788 million adults were living with chronic kidney disease in 2023, nearly double the number in 1990.
Diabetes: The Leading Cause
Persistently high blood sugar damages the tiny blood vessels inside your kidneys. Each kidney contains roughly one million filtering units called glomeruli, and each one is packed with microscopic capillaries. These capillaries act like a sieve: water, minerals, and waste products pass through, while larger molecules like proteins and red blood cells stay in the bloodstream. When blood sugar stays elevated for years, those capillary walls thicken and scar. The filters become leaky, letting protein spill into your urine, and eventually they stop filtering altogether.
Both type 1 and type 2 diabetes carry this risk. The damage is gradual, often taking a decade or more before symptoms appear. By the time you notice changes like foamy urine or swelling in your legs, significant kidney tissue may already be scarred beyond repair.
High Blood Pressure and Blood Vessel Damage
Chronic high blood pressure forces blood through the kidneys’ delicate vessels at harmful intensity. Over time, the walls of the small arteries feeding each filtering unit thicken and stiffen, a process that narrows the space blood flows through. With less blood reaching the filters, kidney tissue becomes starved of oxygen. The filters collapse, the surrounding tubules shrink, and scar tissue fills in the gaps. This chain of events is called nephrosclerosis, and it progresses silently for years.
The relationship also works in reverse. As kidneys lose function, they become worse at regulating blood pressure, which accelerates the damage. This feedback loop is one reason kidney disease tends to worsen steadily once it starts.
Medications That Harm the Kidneys
Drug-induced toxicity accounts for roughly 20% of all kidney injury cases. Some of the most common culprits are available without a prescription. NSAIDs like ibuprofen and naproxen alter blood flow within the kidneys and can trigger inflammation in the tissue between the filtering units. Occasional use is generally fine for healthy kidneys, but regular or high-dose use over months or years raises the risk substantially.
Prescription medications can cause problems too. Certain antibiotics, antiviral drugs, chemotherapy agents, and immune-suppressing drugs are known to be hard on the kidneys. The damage shows up in different ways depending on the drug: some cause crystals to form inside kidney tissue, others poison the tubules directly, and others provoke an inflammatory reaction. If you take any medication long-term, periodic blood work to check kidney function is a straightforward way to catch problems early.
Sudden Kidney Failure
Not all kidney failure builds slowly. Acute kidney injury can develop over hours or days, and it has distinct causes. Severe infections that reach the bloodstream (sepsis) are one of the most common triggers in hospitalized patients. During sepsis, widespread inflammation disrupts blood flow to the kidneys at the microscopic level, damages the energy-producing machinery inside kidney cells, and can shut down filtration rapidly.
Other causes of sudden failure include severe dehydration, major blood loss from trauma or surgery, and a sudden blockage in the urinary tract (from kidney stones or an enlarged prostate, for example). Unlike chronic kidney disease, acute kidney injury is sometimes fully reversible if the underlying cause is treated quickly. But repeated episodes increase the long-term risk of permanent damage.
Genetic and Autoimmune Conditions
Polycystic kidney disease is the most well-known inherited cause of kidney failure. Fluid-filled cysts grow throughout both kidneys over decades, gradually replacing functional tissue. Because the condition is genetic, it often runs visibly through families, with multiple generations needing dialysis or transplant.
Autoimmune diseases can attack the kidneys from a different angle. In lupus, the immune system loses its ability to distinguish the body’s own cells from foreign threats. It produces antibodies against normal cell components, and these antibodies form clumps that deposit in the kidneys’ filters, triggering chronic inflammation. The immune system essentially treats the kidneys as an infection site. Because the underlying immune memory persists even with treatment, lupus-related kidney disease tends to flare and recur over a lifetime.
Lifestyle Factors That Speed Up Damage
Obesity places extra mechanical and metabolic demand on the kidneys. Larger body mass means more blood to filter, and the excess fat tissue produces inflammatory signals that stress kidney cells over time. Obesity also raises the risk of developing diabetes and high blood pressure, compounding the danger.
Smoking constricts blood vessels throughout the body, including those supplying the kidneys, and accelerates the hardening of arterial walls. For someone who already has early kidney disease, smoking can significantly speed progression toward failure. Even in otherwise healthy people, long-term smoking is associated with reduced kidney function.
Chronic dehydration and diets very high in sodium or processed sugar also force the kidneys to work harder. None of these factors typically cause failure on their own, but they amplify the damage from other conditions already at work.
How Kidney Function Is Measured
Doctors track kidney health using a number called the glomerular filtration rate, or GFR, which estimates how much blood your kidneys filter per minute. A normal GFR is 90 or above. Between 60 and 89, function is mildly reduced but rarely causes symptoms. The range of 30 to 59 represents moderate loss, where fatigue and fluid changes may start to appear. Below 30, kidney function is severely compromised. A GFR under 15 is classified as kidney failure, the point where dialysis or transplant becomes necessary to survive.
Because early-stage kidney disease produces no symptoms, the only way to detect it is through blood and urine tests. A simple blood draw measuring creatinine (a waste product your muscles produce at a steady rate) is enough to estimate GFR. Urine tests that detect protein leaking through damaged filters can catch problems even earlier.
What Kidney Failure Feels Like
When the kidneys can no longer clear waste effectively, toxins build up in the bloodstream, a condition called uremia. The symptoms are wide-ranging because those toxins affect nearly every organ system. Nausea, loss of appetite, and a persistent metallic or ammonia-like taste in the mouth are common early signs. Fatigue becomes overwhelming, not the ordinary tiredness of a long day but a deep, unrelenting exhaustion.
As waste levels climb higher, the nervous system suffers. Muscle cramps, restless legs, trouble concentrating, and memory problems can all develop. Fluid that the kidneys can no longer remove backs up in the body, causing swelling in the ankles and feet, puffiness around the eyes, and shortness of breath as fluid collects in the lungs. Skin often becomes dry and intensely itchy. In advanced cases, urea crystals can deposit on the skin as a white residue called uremic frost, and the breath takes on a urine-like odor.
These symptoms typically don’t appear until kidney function has dropped below about 20 to 25% of normal. That long silent period is exactly why kidney disease is called a “silent killer”: by the time you feel something is wrong, the damage is extensive.