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Chemotherapy can save or extend lives by targeting and destroying cancer cells. It can also affect other organs, including the kidneys, which filter waste, balance fluids and minerals, and help control blood pressure.

When kidney health becomes compromised, serious health problems can develop. Understanding how chemotherapy affects kidney health is essential for patients and caregivers.

How Chemotherapy Affects Kidney Function

The kidneys process and remove chemotherapy drugs. Though many patients tolerate this well, sometimes chemotherapy can harm the tiny filters in the kidneys and limit how well they work.

Common chemotherapy drugs that affect the kidneys

The kidneys process many drugs. These include chemotherapy, antibiotics, antivirals, and pain medicines. Some can temporarily stress or damage kidney tissue, altering how well they filter blood.

Before prescribing chemotherapy, providers carefully weigh the benefits and risks.

Many common chemotherapy drugs can affect how well the kidneys filter waste and regulate fluids, including:

• Carboplatin
• Cisplatin
• Gemcitabine
• Ifosfamide
• Methotrexate
• Mitomycin C

Signs of Chemotherapy-Related Kidney Damage

Kidney damage may develop slowly over time or appear suddenly. This is especially the case during intensive treatments like chemotherapy.

Recognizing early warning signs is important in the interest of catching and managing problems quickly. Providers will also help by routinely monitoring kidney function with lab draws.

Patients should watch for:

• Changes in urination — Less urine, very dark urine, or foamy urine that looks unusual.
• Confusion or difficulty concentrating — Waste buildup can affect brain function.
• Fatigue or weakness — A possible result of toxins and waste products building up in the blood.
• Muscle cramps — Especially in the legs, this can have something to do with imbalances in electrolytes like potassium and calcium.
• Nausea, vomiting, or poor appetite — Signs of possible toxin buildup when the kidneys aren’t filtering well.
• Shortness of breath — Fluid retention can affect the lungs and breathing.
• Swelling (edema) — Puffiness in the ankles, feet, hands, or around the eyes caused by fluid buildup.

Know that these symptoms aren’t specific to kidney damage. They’re possible signs of dysfunction, but not always. If you notice symptoms, speak to your doctor to get the full picture.

Risk Factors Beyond Chemotherapy

Not everyone has the same risk with chemotherapy. Factors that increase risk include:

• Chronic kidney disease — Existing kidney problems make damage more likely.
• Dehydration — Low fluid levels reduce kidney protection.
• Diabetes — High blood sugar harms the kidneys over time.
• High blood pressure — Puts extra strain on kidney function.
• Older age — Kidney function naturally declines with age.
• Other drugs — Some antibiotics, pain relievers, and imaging dyes add risk.

Monitoring Kidney Health During Chemotherapy

During treatment, kidney performance can shift quickly, making frequent checks essential. Providers monitor this closely through blood work, urine tests, and other assessments to detect changes early and adjust care as needed.

The below are examples of tests used, but not all are part of a routine check. Your provider will determine the tests you need.

Blood tests

• BUN — Measures waste in the blood.
• Creatinine — Shows how well the kidneys are filtering and is the main check for monitoring changes over time.
• Electrolytes — Tracks sodium, potassium, calcium, and other minerals.
• Estimated glomerular filtration rate (eGFR) — Estimates overall kidney function.

Urine tests

• Protein — Early sign of kidney damage.
• Urine volume — Amount of urine the body makes.

Other tools

• Imaging — Useful when determining the cause of a sudden kidney injury.
• Kidney biopsy — Rarely used but can explain unclear damage in special circumstances.

Strategies to Protect Kidney Function

Several steps protect the kidneys during chemotherapy treatment. These include staying well hydrated and adjusting medications. They also include avoiding other substances that strain the kidneys.

Hydration support

Getting enough fluids is one of the best forms of protection. Patients receiving certain medications often receive IV fluids before and after chemotherapy. This is so they can dilute and wash out the drug.

Other ways patients can support hydration include:

• Carrying a water bottle — Keep water nearby and sip often throughout the day.
• Choosing hydrating foods — Fruits like watermelon and oranges, or vegetables like cucumbers and celery, add extra fluids.
• Drinking in small amounts — If nausea is a problem, try small sips of water, broth, or clear juice more often instead of large amounts at once.
• Setting reminders — Phone alarms or hydration apps can help patients stay on track.
• Trying flavor options — Adding a splash of lemon, lime, or sugar-free flavoring may make water easier to drink.

The daily recommended fluid intake is 15.5 cups or 3.7 liters for men and 11.5 cups or 2.7 liters for women. However, speak with your doctor about what your specific needs are based on your health and conditions.

Medication adjustments

Sometimes, protecting the kidneys means changing how you get chemotherapy. Health care providers may adjust the type of drug, the amount, or the timing. This can reduce stress on the kidneys while still treating the cancer.

They customize changes to patient health and lab results. For example:

• Alternative drugs — They may choose less harmful medicines for high-risk patients.
• Dose changes — Providers may reduce doses or spread out treatments.
• Protective agents — Certain medicines can help reduce kidney injury.

Avoiding extra stress on the kidneys

Patients often learn they should avoid unnecessary pain relievers like nonsteroidal anti-inflammatory drugs (NSAIDs) to lower the risk of extra stress. NSAIDs are a common group of medications taken to reduce pain, fever, and inflammation.

Another possible factor that can cause stress is contrast dyes. Scans use these during treatment. Your provider will determine whether they’re necessary.

These substances can place extra strain on the kidneys, which are already working hard to process chemotherapy drugs. For example:

• NSAIDs — Over-the-counter (OTC) pain relievers such as ibuprofen and naproxen can reduce blood flow to the kidneys. This added stress increases the chance of kidney injury during chemotherapy. Ask your provider if these are safe for you to take. Your provider may recommend alternatives like acetaminophen.
• Contrast dyes — CT scans or MRIs sometimes require these dyes. They can temporarily damage kidney function. If you need imaging, your provider may choose non-contrast scans. They may also use smaller amounts of dye or give IV fluids before and after the procedure. This can help protect the kidneys.

When Kidney Damage Becomes Severe

In rare cases, kidney damage is severe enough that patients need dialysis. Dialysis is a treatment that helps remove fluid and waste when the kidneys aren’t working. Dialysis is short-term when it’s helping the body until the kidneys recover. It’s long-term if the damage is permanent.

Partnering With Your Health Care Team

Patients can play an active role in protecting their kidneys during chemotherapy. Though providers complete regular monitoring and treatment adjustments, daily choices can make a difference. Simple steps and open communication with the care team may help catch problems early and reduce complications.

• Attend all lab visits — Blood and urine tests catch problems early.
• Discuss all medications — Include OTC drugs and supplements.
• Report new symptoms — Share swelling, fatigue, or decreased urination right away.
• Stay hydrated — Drink fluids as recommended by your provider.

Chemotherapy can affect kidney function in ways that range from mild and reversible to severe and lasting. With careful monitoring and personalized treatment, our providers will help you fight cancer while preserving kidney function and quality of life as much as possible.