OTC Medication give kidney damage (maybe)

OTC Medication may give kidney damage. We talk a lot about the continued use of triptans and non-prescription medicines causing chronic daily headache. Thes headache develops fairly rapidly, and can not be overlooked. 

But we do not hear that over the counter medication including aspirin, ibuprofen, paracetamol and NSAIDs probably also can cause kidney damage. Therefore Migrænikerforbundet has looked into recent years of scientific studies on the subject. 

Over the counter painkillers marketed as (in alphabetical order for each substance):

How much non-prescription medicines you take?

A migraineur may combine triptans and OTC medicine for many years, maybe to keep triptan consumption down. With a consumption of 100 grams of aspirin a year or approximately 15 tablets a month for 30 years, you have actually taken 3 kg total dose, probably without feeling that you have taken a particularly high dose. If you have headaches every day is not unlikely that you take 3 pills with ½ g active substance per day. This is equivalent to ½ kg per year. 

Consumption can quickly run up in large quantities.

Many scientific studies from various countries have shown that heavy users of aspirin and paracetamol (called acetaminophen in USA) have an increased incidence of chronic kidney damage. Common to these studies is that the doctors interviewed patients who came to them because they had kidney problems and was asked  about their use of OTC drugs. Doctors have also asked a control group who had renal damage about their consumption, and it appears generally that the patients who have kidney damage, also have taken more OTC drugs than those who do not develop kidney problems. 

Scientific research must be credible - an essential element of good science is to make sure that you do not draw the wrong conclusions. Meanwhile, there ethical issues when working with people. The perfect study that selects a large number of healthy people and ask them to take an agreed amount of medicine for many years pose the patients at risk for developing kidney damage, is obviously not possible. Therefore we do not know the patients' actual use of OTC medications, and we do not know whether those who developed kidney problems, were particularly susceptible to these problems even before they began taking the medication. 

Animal studies indicate that kidney tissue is destroyed. Scientists have obviously made animal testing of drugs, and here it turns out that a daily, relatively high consumption of both pain relievers non-prescription medicine and arthritis means destroying parts of the filtering tissues found in the kidneys. But, argues the most critical scholars, it is not certain that the rat and human kidneys react in exactly the same way to drugs. So we can not be sure that the animal findings also can be relevant for humans. 

A tentative conclusion was published in 1998  by two American scientists in a review article on the relationship between consumption of OTC drugs and renal failure (1). They pointed out that 9 large studies were based on patients who had approached the study because of kidney problems and that they really were not 'controlled experiments', which conclusively showed a correlation. The researchers concluded that until results from controlled trials are available it is prudent to assume that  over the counter pain killers can cause kidney damage at high consumption. 

In 2000 came another review article (2). This time, with thanks to the pharmaceutical industry. The researchers concluded in this article that 'there is insufficient basis to conclude that the  over the counter medications with caffeine can cause kidney damage'. Researchers assumed in this context that medicine with caffeine would be worse than those that contained only the active analgesic drug(s). However, there was general agreement that the substance phenacetin, which is removed from the market many years ago, is likely to have caused some kidney problems. 

There are significant differences between the two conclusions. A statement from 1998 says it can not be excluded that consumers taking large amounts of pain killers have kidney damage, while from 2000 says there is no basis for believing that large amounts of painkillers containing caffeine give kidney damage. Seen from the users point of view the first means that we must be cautious, while the other says there is reason for caution. 

What say kidney patient organizations?

The Internet is full of websites that recommend that you should be aware that there may be kidney damage due to a large consumption of OTC drugs (search on the phrase 'analgesic Nephropathy' - it is the English name for kidney damage (Nephropathy) caused by painkiller (analgesic ) medicine). The most often mentioned estimate is that a total consumption of between 2 and 3 kg active ingredient provides a significantly increased risk for developing kidney damage. For the individual patient, it is better to be a little careful with the consumption of these substances than to get kidney damages which can only be repaired with dialysis or kidney transplantation. 

3 kg active ingredient corresponds to 6000 pills with ½ g active ingredient. 

6000 pills similar to: 

1 pill a day for 20 years 

or 

2 pills a day for 10 years 

or 

6 pills a day for 3 years 


How does kidney damage show up? 

Symptoms appear gradually, as more and more tissue in the kidneys become damaged.The healthy tissue continues to filter the urine, and you feel nothing special for a long time. Perhaps there is little blood and white blood cells in urine but no bacteria, and usually there is no protein in the urine. 

When the damage in the kidneys become more pronounced there will be symptoms like fatigue, larger (or smaller) amount of urine, blood in the urine, pain in the sides or back, reduced sensation in hands and feet, tendency to bruise very easily, and perhaps also swollen feet and hands. 

Can kidney injury healed?

In general, chronic kidney damage is not curable. The kidneys are not restored, and no new filter tissue is formed in adults. 

The only sensible advice is to be careful not to take too many doses of the drugs that may cause damage. And, at the slightest suspicion that there may be emerging serious injuries, put the pain killers on the shelf. 

But we are in need of OTC medication!

All migraineurs need OTC's now and again, to soothe the last remnants of an attack, or to treat pain for quite different reasons than migraine, fever and all those mall aliments other people use OTC drugs for. It is wise to keep an eye on the consumption of aspirin, paracetamol, ibuprofen and anti-inflammatory drugs (NSAIDs), so they can still be used for what they are specifically good at, to treat joint pain (NSAIDs and ibuprofen) and antipyretic drugs (aspirin and paracetamol). 

(1) E. Delzell and S. Shapiro, 1998. A Review of Epidemiologic Studies of Nonnarcotic Analgesics and Chronic Renal Disease. Medicine 77, 102-21. 

(2) A. R. Feinstein, L. A. J. Heinemann, G. C. Curhan, E. Delzell, P.J.  DeSchepper, J. M. Fox, H. Graf, F. C. Air, P. Michielsen, M. J. Mihatsch, S. Suissa, F. vd Woude and S. Willich, 2000.Relationship mellom nonphenacetin combined analgesics and Nephropathy: A Review. Kidney International 58, 2259-2264.