Analgesic Nephropathy (Painkillers and the Kidneys)

An analgesic (AN-ul-JEE-zik) is any medicine intended to relieve pain. Over-the-counter analgesics (medicines bought without a prescription) include aspirin, acetaminophen, ibuprofen, naproxen sodium, and others. These drugs present no danger for most people when taken in the recommended dosage. But some conditions make taking even these common painkillers dangerous for the kidneys. Also, taking one or a combination of these drugs regularly over a long period of time may increase the risk for kidney problems. Most drugs that can cause kidney damage are excreted only through the kidneys.

Analgesic use has been associated with two different forms of kidney damage. Some patient case reports have attributed incidents of sudden-onset acute kidney failure to the use of over-the-counter painkillers, including aspirin, ibuprofen, and naproxen. The patients in these reports had risk factors such as systemic lupus erythematosus, advanced age, chronic kidney disease, or recent heavy alcohol consumption. These cases involved a single dose in some instances and generally short-term analgesic use of not more than 10 days. Acute kidney failure requires emergency dialysis to clean the blood. Kidney damage is frequently reversible, with normal kidney function returning after the emergency is over and the analgesic use is stopped.

A second form of kidney damage, called analgesic nephropathy, can result from taking painkillers every day for several years. Analgesic nephropathy is a chronic kidney disease that over years gradually leads to irreversible kidney failure and the permanent need for dialysis or a kidney transplant to restore renal function.

Longstanding daily use of painkillers composed of two or more analgesics (particularly aspirin and acetaminophen together) with caffeine or codeine are most likely to damage the kidneys. These mixtures are often sold as powders or tablets. Recent studies have suggested that longstanding daily use of single analgesics such as acetaminophen or ibuprofen may also increase the risk of chronic kidney damage, but this evidence is not as clear.

In view of these findings, patients with conditions that put them at risk for acute kidney failure should check with their doctors before taking any analgesic medicine. People who take over-the-counter painkillers on an ongoing and regular basis should check with their doctors to make sure the drugs are not hurting their kidneys. The doctor may be able to recommend a safer alternative.