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 biggest causes are diabetes and high blood pressure, which together account for the majority of chronic cases. But kidney failure can also strike suddenly from dehydration, infections, medication damage, or physical blockages. About 14% of U.S. adults have some degree of chronic kidney disease, and many don’t know it until the damage is advanced.
Understanding what drives kidney failure matters because the causes fall into distinct categories, each with different warning signs and timelines. Some develop over years. Others can happen in days.
Diabetes and High Blood Pressure
These two conditions are responsible for most chronic kidney failure, and they damage the kidneys through related but distinct mechanisms.
In diabetes, persistently high blood sugar overloads kidney cells with glucose and fatty acids. This overwhelms the cells’ energy-producing machinery (the mitochondria), generating harmful molecules called reactive oxygen species that damage tissue from the inside. Over time, high sugar levels also cause scarring in the kidney’s tiny filtering units, called glomeruli, and force blood through those filters faster than normal. The combination of scarring and overwork gradually destroys the filters.
High blood pressure damages the kidneys more mechanically. Elevated pressure in the blood vessels feeding the glomeruli destroys the delicate capillary walls. Specialized cells called podocytes, which sit on those capillaries and control what passes through, begin to malfunction. Protein starts leaking into the urine, an early sign of kidney damage. Over years, the constant pressure causes scarring and inflammation that stiffens and narrows the blood vessels, reducing the kidneys’ ability to do their job.
What makes both conditions especially dangerous is a vicious cycle: as some filtering units are destroyed, the remaining ones compensate by working harder. This hyperfiltration raises pressure inside the surviving glomeruli, which accelerates their damage too. The result is a slow, self-reinforcing decline that can progress silently for a decade or more before symptoms appear. Among people with chronic kidney disease, 35.6% also have diabetes, compared to just 9.5% of adults without kidney disease.
Sudden Kidney Failure
Acute kidney injury develops over hours or days and falls into three broad categories: reduced blood flow, direct kidney damage, and blocked urine drainage.
Reduced Blood Flow
Your kidneys need a steady supply of blood to filter properly. Anything that sharply reduces that supply can cause them to shut down. Common triggers include severe dehydration, major blood loss, heart attack or heart failure, liver failure, serious burns, and dangerous allergic reactions (anaphylaxis). Even blood pressure medications can occasionally drop pressure low enough to starve the kidneys of flow.
Direct Damage to Kidney Tissue
Some conditions and substances injure the kidneys directly. Severe infections, including sepsis and COVID-19, can inflame kidney tissue. Autoimmune diseases like lupus cause the immune system to attack the glomeruli. Toxins like alcohol, heavy metals, and cocaine are directly destructive. Blood clots in or around the kidneys, cholesterol deposits blocking small vessels, and rare blood disorders can also cause acute damage.
Blocked Urine Drainage
When urine can’t drain out of the kidneys, pressure builds up and damages the tissue. Kidney stones are a common culprit. An enlarged prostate can compress the tubes that carry urine from the kidneys to the bladder. Tumors in the urinary tract or nearby organs can have the same effect. If the blockage is caught early and relieved, kidney function often recovers. Left untreated, the backed-up pressure causes permanent damage.
Inflammation of the Kidney Filters
Glomerulonephritis, or inflammation of the glomeruli, is a major category of kidney disease with many possible triggers. It can be acute or chronic, and it sometimes leads to kidney failure on its own.
Infections are one trigger. A strep throat or skin infection can set off an immune response where antibodies build up in the glomeruli a week or two after the infection clears. Hepatitis B, hepatitis C, and HIV can all cause ongoing inflammation in the kidney filters, sometimes before other symptoms of those infections are obvious. Bacterial infections of the heart’s inner lining (endocarditis) are another route.
Autoimmune diseases are a second major trigger. Lupus can attack the kidneys directly, causing what’s known as lupus nephritis, where the immune system deposits antibodies in the glomeruli. A condition called IgA nephropathy occurs when a common type of antibody accumulates in the filters for reasons that aren’t fully understood. In a rare condition called Goodpasture’s syndrome, the immune system creates antibodies that target both lung and kidney tissue simultaneously.
Blood vessel inflammation (vasculitis) can also involve the kidneys. Conditions like polyarteritis and granulomatosis with polyangiitis damage small and medium blood vessels throughout the body, including those in the kidneys.
Medications That Harm the Kidneys
A surprising number of common medications can cause kidney damage, especially with long-term use or in people whose kidneys are already somewhat compromised. Over-the-counter painkillers are among the most frequent offenders. NSAIDs like ibuprofen reduce blood flow to the kidneys, and regular use over months or years raises the risk of chronic damage. Acetaminophen, while generally considered safer for the kidneys at normal doses, can also contribute to damage with heavy or prolonged use.
Prescription medications with kidney-damaging potential include certain antibiotics, chemotherapy drugs, antiretrovirals used for HIV, some antidepressants, diuretics (water pills), proton pump inhibitors used for acid reflux, and even some blood pressure medications. Contrast dyes used in CT scans and other imaging tests can also injure the kidneys temporarily, which is why doctors often check kidney function before ordering these scans.
The risk from any single medication is generally low for people with healthy kidneys. It rises significantly when multiple nephrotoxic drugs are combined, when someone is dehydrated, or when kidney function is already reduced.
Genetic and Inherited Causes
Some people are born with genes that make kidney failure more likely regardless of lifestyle. Polycystic kidney disease is the most common inherited form, causing fluid-filled cysts to grow throughout the kidneys over decades, gradually replacing healthy tissue and reducing function. Alport syndrome is a rarer inherited condition that affects the glomeruli and can also impair hearing and vision.
Researchers have also identified specific genes that make the kidneys more vulnerable to antibody deposition, the process that drives lupus nephritis and similar conditions. One example is a gene called VANGL1, which appears to predispose the kidney itself to accumulating antibodies, independent of how active the immune system is. This helps explain why some people with lupus develop severe kidney disease while others with equally active lupus do not.
How Kidney Damage Is Measured
Doctors gauge kidney function using a blood test that estimates how well your kidneys filter waste, expressed as a number called the estimated glomerular filtration rate (eGFR). A normal eGFR is above 90. If yours stays below 60 for three months, that typically qualifies as chronic kidney disease. Stage 5, the most severe, indicates kidney failure and usually means dialysis or a transplant is needed.
The tricky part is that kidneys can lose a significant amount of function before you feel any different. The compensatory hyperfiltration that remaining nephrons perform masks the decline for years. By the time symptoms like fatigue, swelling, or changes in urination become noticeable, kidney function may already be substantially reduced. This is why routine blood and urine tests are important for anyone with diabetes, high blood pressure, a family history of kidney disease, or regular use of medications that affect the kidneys.