Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used medications and several products containing NSAIDs are available without a doctor’s prescription. These include ibuprofen (Nurofen brand), diclofenac (Voltaren brand) and naproxen (Naprogesic brand).

Since 2003, ibuprofen has been openly sold in Australia in retail outlets where professional advice is not available. While NSAIDs offer great benefit in treating a variety of painful and inflammatory musculo-skeletal conditions, they are potent drugs and carry the risk of a wide spectrum of well-documented side effects. Prominent among these, NSAID-induced gastrointestinal side effects, including stomach ulcers and bleeding from the gut, are well established, well publicised and well understood by the  public.

However, a more insidious side effect of NSAIDs, and one that is too often overlooked even by health professionals advising patients, is the potential for NSAIDs, either used alone or in combination with some other medications under certain conditions, to inhibit the vital role of the kidneys in filtering out waste products from the blood, for excretion in urine and returning the filtered blood to the circulatory system.

Prostaglandins play a critically important role in ensuring adequate filtration pressure in the glomerular section of kidney, when the blood supply to the kidney is reduced, which can occur due to fluid loss or dehydration, associated with diarrhoea or vomiting.

In such situations, NSAIDs, being anti-prostaglandin drugs, can lead to — albeit temporary — kidney failure, which, if left uncorrected, could obviously have life-threatening consequences.

This type of kidney damage can occur in dehydrated, but otherwise healthy individuals. Indeed, there have been many case reports of renal (kidney) toxicity in dehydrated but otherwise healthy children given NSAIDs.

Two recent papers emphasised the potential for the onset of acute renal failure due to volume depletion, as a result of giving NSAIDs during bouts of diarrhoea or vomiting. What is especially disturbing in this context, is that the justification usually cited for lack of toxicity to the kidneys of NSAIDs when used in children and infants is a 1997 re-analysis of a 1995 study, which specifically excluded all children who were 10% or more dehydrated.

Also of concern is that when NSAIDs are given to people suffering from high blood pressure, who take ACE or ARB-containing medications combined with a diuretic to enhance fluid excretion, this so-called “triple whammy” combination can add to the the underlying NSAID risk of acute kidney failure, especially where there is fluid loss associated with diarrhoea or vomiting. Triple whammy events make up about 50% of reports to the Australian Drug Evaluation Committee (ADRAC) of drug-induced acute kidney failure and 10% of these end in fatality.

While over-the-counter packs of NSAID products do carry warnings about existing kidney disease as a contra-indication to their use, there are no warnings about the potential risk of kidney damage from taking NSAIDs when dehydrated through diarrhoea or vomiting, as can often occur during episodes of fever or high temperature — the very time that NSAIDs are taken for symptomatic relief.

The time is long overdue for the Therapeutic Drugs Administration to mandate warnings on all packs of non-prescription NSAID products, about the potential risk of kidney damage during episodes of fluid loss of any type.