Drug-induced nephropathy: when a medicine harms the kidneys

The kidneys filter the blood, which means they are exposed to high concentrations of anything the body is trying to get rid of, including medicines and their breakdown products. Drug-induced nephropathy is the name for kidney damage that results when a medicine, a contrast dye or some other chemical harms the kidney, either suddenly (acute kidney injury) or over months and years (chronic kidney disease).

Different medicines act in different ways. Some reduce the blood flow to the kidneys, some inflame the tissue between the filters, and some are directly toxic to the kidney cells. In many cases the medicine is perfectly appropriate and safe for most people, and trouble arises only when another factor, such as dehydration, illness or existing kidney disease, tips the balance. That is why dose, hydration and the other medicines being taken are reviewed so carefully.

NICE Clinical Knowledge Summaries give lists of agents that matter. These do not mean the medicines are dangerous for everyone; they mean extra care is needed in people with other risk factors.

Drug-related kidney damage frequently causes no symptoms at first, and may be found only from a blood test. When symptoms occur, they resemble those of AKI generally. The NHS lists peeing much less than usual, feeling very thirsty, nausea or vomiting, swollen feet or legs, feeling tired, dizzy, confused or sleepy, and breathlessness, especially when lying down.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you think you may have symptoms of acute kidney injury. For people taking NSAIDs, the NHS names shortness of breath, blood in the pee or swelling in the ankles, feet or hands as signs of kidney problems and says some rare but serious side effects may need advice from NHS 111.

Never stop a medicine that was prescribed for a heart, blood pressure, diabetes or other condition just because of a worry about the kidneys. Ask your GP or pharmacist; they can check your blood tests and advise whether to continue, change the dose or pause the medicine.

NICE CKS list those at increased risk of AKI as people aged 65 or over, with a history of AKI, with chronic kidney disease, heart failure, liver disease or diabetes, who are dehydrated or have sepsis, who rely on others for fluids, and who have used medicines such as NSAIDs, ACE inhibitors, angiotensin receptor blockers, diuretics and aminoglycoside antibiotics in the last week, especially if low in fluid. Exposure to iodine-based contrast in the past week is also listed.

Combining several of these factors raises the chance of harm. For example, someone with diarrhoea and vomiting who continues taking an anti-inflammatory painkiller, a blood pressure tablet and a water tablet is at higher risk than the same person well and drinking normally.

Kidney function is checked with a blood test for creatinine, and a urine test can show protein or blood. The NHS says AKI is diagnosed using a blood test, and that higher creatinine levels than usual mean the kidneys are not working as well as they should. NICE CKS add that a diagnosis may be made when creatinine rises by 26 micromol/L or more within 48 hours or by 50% or more within the past 7 days.

For long-term effects, the NHS says chronic kidney disease can be diagnosed using blood and urine tests, which are used to stage the condition, and that people at high risk may be advised to have regular tests. NICE CKS describe CKD as an abnormality of kidney function or structure present for more than 3 months, and note that nephrotoxic drugs are among its causes.

If the cause is unclear, doctors may also arrange an ultrasound scan and a kidney specialist review. They will go through a full list of prescribed, over-the-counter and herbal medicines, because supplements and remedies can be relevant.

The mainstay of treatment is to stop or change the medicine that may be causing harm, on medical advice, and to support the kidneys while they recover. The NHS lists stopping or changing any medicine that could be causing damage, giving fluids through a drip and treating infection or other causes. Kidney Care UK describes sick day rules, in which doctors advise temporarily stopping or adjusting some medicines during illness and review them once kidney function recovers.

If AKI is severe, dialysis may be used for a few days or weeks until the kidneys recover, according to the NHS. For kidney disease that develops over a long time, the NHS says there is no cure, but treatment can help relieve symptoms and slow progression, with medicine to control blood pressure and cholesterol, lifestyle measures and regular check-ups.

The NHS advises people at higher risk of AKI to stay hydrated, drinking enough that pee is pale and regular, especially in hot weather or when being sick or having diarrhoea, to speak to a doctor before taking new medicines or supplements, and to know the symptoms to watch for.

Practical steps include telling every prescriber and pharmacist that you have had kidney problems, asking whether over-the-counter anti-inflammatories are suitable, and attending the blood test reviews that go with long-term medicines. NICE CKS also advise reviewing the need for medicines that were stopped or reduced during an AKI episode.

Many cases are reversible once the cause is removed. The NHS says many people with AKI recover fully within a few weeks, while some end up with permanent damage and chronic kidney disease, especially after severe AKI or when other long-term conditions are present. CKD that results from long-term medicine use may need monitoring for life, but the NHS notes that most people with CKD can control the condition with medicine and regular check-ups.