Learn About Medications and Kidney Health Information

Understanding How Kidneys Work and Why They Matter

Your kidneys are two bean-shaped organs about the size of your fists, located on both sides of your spine below the rib cage. Most people have two kidneys, though some people are born with one kidney or lose one kidney during their lifetime. The kidneys perform several critical functions that keep your body healthy and balanced every single day.

The primary job of your kidneys is to filter waste products and extra water from your blood to create urine. Your body produces waste constantly through normal metabolic processes—breaking down food for energy, repairing cells, and building new tissue all generate byproducts that need to be removed. Without functioning kidneys, these waste products would accumulate in your bloodstream and become toxic. Each day, your kidneys filter about 120 to 150 quarts of blood to produce approximately 1 to 2 quarts of urine, which stores waste until you urinate.

Beyond waste removal, kidneys regulate several other essential body functions. They control blood pressure by managing the amount of fluid in your body and the tension in blood vessel walls. Kidneys produce hormones that help create red blood cells, which carry oxygen throughout your body—a hormone called erythropoietin signals your bone marrow to produce more red blood cells when oxygen levels drop. Your kidneys also regulate the balance of electrolytes like sodium, potassium, and phosphorus, which are minerals your body needs for nerve signals, muscle contractions, and heart rhythm. Additionally, kidneys activate vitamin D, which helps your body absorb calcium for strong bones.

When kidneys function well, they maintain this delicate balance automatically. However, when kidney disease develops, these functions gradually decline. According to the National Kidney Foundation, about 37 million American adults have chronic kidney disease, though many don't know it because kidney disease often has no symptoms in early stages. Understanding how your kidneys work helps explain why protecting them and monitoring their health is so important.

Practical Takeaway: Your kidneys filter waste, regulate blood pressure, produce hormones, and balance electrolytes—all essential for survival. Learning about these functions helps you understand why kidney health matters and how certain medications can affect your kidneys.

How Medications Affect Kidney Function

Many common medications can affect how your kidneys work, either by changing kidney function directly or by altering the balance of substances your kidneys must regulate. Understanding this relationship is important because your kidneys must process and eliminate most medications from your body. When your kidneys aren't working properly, medications can build up to harmful levels in your bloodstream instead of being filtered out through urine.

Some of the most commonly used medications that can impact kidney function include nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen. These pain relievers are available over-the-counter and are used by millions of people for headaches, arthritis, and other pain conditions. NSAIDs work by reducing inflammation, but they can also reduce blood flow to the kidneys, potentially leading to acute kidney injury, particularly in people who are dehydrated, elderly, or who already have kidney disease. Acetaminophen, a different type of pain reliever, is generally considered safer for the kidneys when taken at recommended doses.

Blood pressure medications, while essential for protecting kidneys in many cases, can also affect kidney function depending on the type. ACE inhibitors and angiotensin receptor blockers (ARBs) are often prescribed specifically because they protect kidney function in people with diabetes or high blood pressure. However, certain blood pressure medications may reduce kidney function in some patients. Diuretics, sometimes called water pills, help lower blood pressure by increasing urine output, but they can cause dehydration if not monitored carefully.

Diabetes medications also require attention regarding kidney health. Some newer diabetes medications like SGLT2 inhibitors have shown protective effects on kidney function, while others may require dose adjustments as kidney function declines. Antibiotics represent another medication class that can affect kidneys—some antibiotics like aminoglycosides can cause kidney damage, particularly with prolonged use or in people with existing kidney problems. Contrast dye used during certain medical imaging procedures can also temporarily reduce kidney function, especially in people with pre-existing kidney disease or diabetes.

The relationship between medications and kidney function depends on several factors: your age, your current kidney function, whether you have diabetes or high blood pressure, how much of the medication you take, how long you take it, and whether you're taking multiple medications that interact with each other. A medication that's safe for someone with healthy kidneys might be dangerous for someone with kidney disease.

Practical Takeaway: Common medications including pain relievers, blood pressure drugs, diabetes medications, and antibiotics can all affect kidney function. Talk with your doctor or pharmacist about how any medication you take might impact your kidneys, especially if you have risk factors for kidney disease.

Recognizing Kidney Disease and When to Monitor Your Kidneys

Chronic kidney disease often develops silently without noticeable symptoms, which is why it's sometimes called a "silent disease." Many people don't realize their kidneys aren't functioning normally until the disease has progressed significantly. However, certain groups of people should monitor their kidney function more closely because they face higher risk of developing kidney disease.

You have higher risk for kidney disease if you have diabetes, high blood pressure, a family history of kidney disease, are age 60 or older, or belong to certain racial or ethnic groups—African Americans, Hispanic Americans, Native Americans, and Pacific Islander Americans have higher rates of kidney disease. Additionally, if you have heart disease, are overweight, smoke, or have had acute kidney injury in the past, your risk increases. People who take NSAIDs regularly or who use certain herbal supplements also face increased risk.

When kidney disease does cause symptoms, they typically appear only after significant kidney damage has occurred. Possible signs include fatigue and weakness (from anemia or electrolyte imbalances), shortness of breath, swelling in the feet, ankles, hands, or face (from fluid retention), nausea or vomiting, difficulty concentrating or "brain fog," muscle cramps, and changes in urination patterns—urinating more or less frequently, or noticing blood in urine or foamy urine. High blood pressure that's difficult to control can also indicate kidney problems. However, these symptoms can also indicate many other conditions, so medical testing is necessary for diagnosis.

Your doctor can measure kidney function through blood tests and urine tests. The most common blood test measures creatinine, a waste product produced by muscles that healthy kidneys filter out. Your doctor uses creatinine levels along with your age, sex, and race to calculate your estimated glomerular filtration rate (eGFR), which indicates how well your kidneys are filtering waste. An eGFR of 60 or higher is considered normal kidney function. A urine test can detect protein or blood, which shouldn't normally be present in urine if kidneys are working properly. Proteinuria—protein in the urine—is often an early sign of kidney disease.

Kidney disease is categorized into five stages based on eGFR. Stage 1 means normal kidney function but with signs of kidney damage; Stage 2 means mildly reduced kidney function; Stage 3a and 3b mean moderately reduced kidney function; Stage 4 means severely reduced kidney function; and Stage 5 means kidney failure requiring dialysis or transplant. Your doctor will determine your kidney disease stage through testing.

Practical Takeaway: If you have diabetes, high blood pressure, or are age 60 or older, ask your doctor about kidney function testing. Regular monitoring through blood and urine tests can catch kidney problems early, when treatments are most effective.

Medication Safety When You Have Kidney Disease

If you've been diagnosed with kidney disease, medication management becomes increasingly important. As kidney function declines, your body handles medications differently, and doses that work for people with healthy kidneys may be too much for you. Your doctor or pharmacist must adjust many medications based on your kidney function level, measured by your eGFR and creatinine clearance.

Some medications must be avoided entirely when kidney disease is present. NSAIDs should generally be avoided or used only under close medical supervision because they can worsen kidney function. Certain antibiotics are contraindicated—meaning they shouldn't be used—in kidney disease. Some herbal supplements, including those containing creatine, can be harmful. Even over-the-counter medications containing high