Chemotherapy when your kidneys are not working fully

Usually, yes. Kidney disease rarely rules out chemotherapy on its own. More often it changes the plan: the choice of medicines, the amount given, how fluids are managed and how closely blood tests are watched. The kidneys remove many chemotherapy medicines and their breakdown products from the body. When kidneys work less well, some medicines stay in the body longer and can cause stronger side effects, so your oncologist may reduce the amount, space treatments differently, or choose a different medicine that relies less on the kidneys. Some medicines, such as cisplatin, can themselves strain the kidneys, and for people with reduced kidney function an alternative such as carboplatin may be considered, with the amount calculated from kidney function.

Before treatment, your kidney function is measured with blood tests, usually creatinine, from which an estimate of filtering ability is calculated, and sometimes with a urine collection or a special scan. These results guide the plan. During treatment, kidney tests are repeated before each cycle, and your team will watch salts such as potassium, sodium and magnesium. Staying well hydrated matters, and some treatments are given with extra fluids through a drip. Sickness, vomiting and diarrhoea can dehydrate you and strain the kidneys, so controlling them is part of protecting kidney function.

Many people with kidney disease also have diabetes, high blood pressure or heart disease, and take medicines for these. Some common medicines, including certain painkillers, can affect the kidneys, and others need adjusting when kidney function changes. Your oncologist and kidney doctor should communicate, and it helps to bring a full list of your medicines to every appointment. Never start, stop or change a medicine on your own; ask your team first.

Adjustment rather than exclusion

For most people, kidney disease changes how chemotherapy is given, not whether it is given.

Painkillers need care

Anti-inflammatory painkillers such as ibuprofen can harm the kidneys. Ask before taking any painkiller.

Contrast scans need planning

Dye used in some CT scans can affect kidneys. Tell the scan team about your kidney disease.

It cannot tell you which chemotherapy or amount is right for your kidney function. That depends on your results, cancer, other conditions and the medicines needed, and must be decided by your oncologist, often with a kidney specialist.

It also cannot interpret your kidney tests. Ask your team to explain what your results mean for your treatment.

Mild, moderate and severe kidney disease

People with mildly reduced kidney function often need few changes. Those with more reduced function may need more adjustments and closer monitoring. People on dialysis can often still receive chemotherapy, with careful timing around dialysis sessions. Your team will explain which situation applies to you.

Kidney problems caused by the cancer

Some cancers, such as myeloma, or blockages from tumours, affect the kidneys directly. Treating the cancer may improve kidney function. Your team may place tubes to relieve blockages before chemotherapy.

Diet and fluids

People with kidney disease may have restrictions on salt, potassium or fluids. During chemotherapy, these may need adjusting, for example when vomiting or diarrhoea occur. Ask a dietitian for advice that balances kidney and cancer needs.

Herbal and traditional remedies

Some herbal and traditional products can harm the kidneys or interact with chemotherapy. Tell your team about anything you take.

Blood pressure and diabetes

Good control of blood pressure and sugar helps protect kidneys during treatment. Keep regular reviews.

Why kidney function can change during treatment

Kidney function can change during chemotherapy for several reasons. Dehydration from vomiting, diarrhoea or poor drinking is a common cause and is often reversible. Some medicines, including some chemotherapy, antibiotics and painkillers, can strain the kidneys. In some fast-growing cancers, tumour breakdown releases substances that the kidneys must clear, and extra fluids or medicines may be given to protect them. Blockages from tumours can also affect kidney drainage. Regular blood tests pick up changes early so the team can act.

Medicines that may be reviewed

If you have kidney disease, your doctors may review medicines such as metformin, some blood pressure tablets, water tablets, some antibiotics and anti-inflammatory painkillers during chemotherapy, especially if you become dehydrated. They may also choose anti-sickness and pain medicines that suit your kidneys. These decisions belong to your doctors, so do not stop or change any medicine without advice, and bring a complete list, including herbal products, to every visit.

Salts and heart rhythm

Some chemotherapy medicines cause the body to lose magnesium and potassium through the kidneys, while kidney disease can make potassium build up. Both low and high levels can affect muscles and heart rhythm. Blood tests check these salts, and supplements or diet changes may be advised. Report muscle cramps, weakness or palpitations.

Protecting kidney function long term

After treatment, keep regular kidney checks with your kidney doctor or physician, control blood pressure and sugar, and avoid unnecessary painkillers.

What to do next

Share your kidney history and test results with your oncologist, bring a full medicine list, ask whether your kidney doctor will be involved, stay hydrated as advised, avoid painkillers unless approved, tell scan teams about your kidneys, and report warning signs promptly.