Both ibuprofen and acetaminophen (Tylenol) can potentially cause kidney damage if taken in high or prolonged doses. However, there are some key differences between these two commonly used over-the-counter pain relievers when it comes to their effects on kidney health.
How ibuprofen affects the kidneys
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). It works by inhibiting cyclooxygenase enzymes, which helps reduce inflammation and pain in the body. However, one of the side effects of NSAIDs like ibuprofen is that they can reduce blood flow to the kidneys. This constriction of blood vessels in the kidneys can lead to acute kidney injury and impairment of kidney function.
Some of the ways ibuprofen may impact kidney health include:
- Reducing glomerular filtration rate (GFR) – GFR is a measure of how efficiently the kidneys are filtering blood. Ibuprofen can cause a dose-dependent decrease in GFR.
- Salt and water retention – Ibuprofen can cause the body to retain more salt (sodium) and water, which increases blood pressure and workload on the kidneys.
- Acute interstitial nephritis – This is inflammation of the kidney tubules and interstitium that can lead to acute kidney injury. It is a rare reaction, but ibuprofen is one NSAID that has been associated with it.
- Chronic kidney disease (CKD) – Long-term use of ibuprofen may be associated with higher risk of developing CKD.
- Acute kidney failure – In cases of overdose, ibuprofen can cause acute failure requiring emergency dialysis treatment.
The risk of kidney damage is increased if ibuprofen is taken in high doses or for prolonged periods. The recommended OTC dose of ibuprofen is no more than 1,200 mg per day for adults and less for children based on weight. Taking more than 3,000 mg per day or regularly over several weeks can start to put strain on the kidneys.
Those already at risk of kidney disease, including the elderly and those with diabetes, hypertension, or heart failure, appear to be more susceptible to renal injury from NSAIDs like ibuprofen. Dehydration or interactions with other nephrotoxic drugs can also increase the kidney risks.
Acetaminophen and the kidneys
Unlike NSAIDs such as ibuprofen, acetaminophen (Tylenol) is considered kidney-friendly at recommended doses. Acetaminophen does not reduce kidney blood flow or directly damage the kidney tubules.
However, acetaminophen still has risks to kidney health in certain situations:
- Overdose – Excessive single or accumulated doses of acetaminophen can cause severe liver toxicity. This can secondarily impact the kidneys, resulting in acute kidney failure.
- Underlying kidney disease – Those with advanced CKD may not excrete acetaminophen as efficiently. Doses may need to be reduced to avoid buildup and liver toxicity.
- Alcohol use – Concurrent alcohol use increases potential liver toxicity from acetaminophen overdose.
The recommended maximum daily dose of acetaminophen is 4,000 mg per 24 hours in healthy adults and less in children. Exceeding this dose, particularly while drinking alcohol, can quickly reach toxic levels that damage the liver. Since the kidneys rely on the liver, acetaminophen overdose can essentially “poison” the kidneys secondarily.
Ibuprofen vs acetaminophen: Which is worse for kidneys?
When comparing ibuprofen and acetaminophen at OTC doses, ibuprofen appears worse in terms of direct harm to the kidneys. Some key points:
- Ibuprofen reduces kidney blood flow; acetaminophen does not.
- Ibuprofen is associated with acute kidney injury and interstitial nephritis; acetaminophen is not.
- Ibuprofen can increase blood pressure and sodium retention; acetaminophen does not.
- Ibuprofen may cause dose-dependent reductions in GFR; acetaminophen does not.
However, acetaminophen still carries risks of kidney damage in cases of overdose, particularly when combined with alcohol intake.
Overall, both medications are considered safe for the kidneys when taken at recommended dosages short-term. But regular, long-term use of ibuprofen appears to pose a greater direct risk to kidney function compared to acetaminophen based on the research.
Protecting kidney health
To reduce risks to the kidneys when using OTC pain medicines like ibuprofen and acetaminophen:
- Take the lowest effective dose.
- Do not exceed maximum recommended doses.
- Use for less than 10 days when possible.
- Stay well hydrated.
- Avoid combining medications without consulting a doctor.
- Monitor for signs of kidney problems like increased creatinine, swelling, or decreased urine output.
- Consult a doctor for pain lasting over 10 days as underlying condition may require different treatment.
Those at higher risk for kidney disease, including older adults and people with diabetes, high blood pressure, or liver conditions, should be especially cautious with any medication use. Speak to a doctor about monitoring kidney function with periodic bloodwork if regularly using NSAIDs or acetaminophen.
Conclusion
Ibuprofen appears to pose a greater direct risk to kidney function compared to acetaminophen, particularly with high or chronic use. However, acetaminophen can also lead to kidney injury in cases of overdose. Using the lowest effective dose, avoiding combining medications, and staying hydrated can help minimize risks to the kidneys with either over-the-counter pain reliever. For persistent pain or if at high risk for kidney disease, speak to a doctor about the safest options for pain management.