By Morgan Nwanguma
The painkillers many of us trust – ibuprofen and acetaminophen (paracetamol), may be quietly worsening one of the world’s most urgent health threats: antibiotic resistance.
In the first study of its kind, researchers at the University of South Australia found that these drugs don’t just drive resistance on their own; they make it far worse when combined with antibiotics. When tested alongside the commonly prescribed antibiotic ciprofloxacin, both painkillers triggered a surge in bacterial mutations, turning E. coli, a frequent cause of gut and urinary tract infections, highly resistant.
The implications are alarming, especially in aged care homes where residents often take multiple medications. Such environments, researchers warn, may create ideal breeding grounds for superbugs.
Antimicrobial resistance already claims more than a million lives each year, according to the World Health Organisation. Lead researcher, Associate Professor Rietie Venter says the findings highlight the hidden risks of polypharmacy in vulnerable populations and the urgent need to rethink how common drugs interact.
“Antibiotics have long been vital in treating infectious diseases, but their widespread overuse and misuse have driven a global rise in antibiotic-resistant bacteria,” Assoc Prof Venter says.
This is especially prevalent in residential aged care facilities, where older people are more likely to be prescribed multiple medications – not just antibiotics, but also drugs for pain, sleep, or blood pressure – making it an ideal breeding ground for gut bacteria to become resistant to antibiotics.
“In this study we looked at the effect of non-antibiotic medicines and ciprofloxacin, an antibiotic which is used to treat common skin, gut or urinary tract infections.
“When bacteria were exposed to ciprofloxacin alongside ibuprofen and acetaminophen, they developed more genetic mutations than with the antibiotic alone, helping them grow faster and become highly resistant. Worryingly, the bacteria were not only resistant to the antibiotic ciprofloxacin, but increased resistance was also observed to multiple other antibiotics from different classes.
“We also uncovered the genetic mechanisms behind this resistance, with ibuprofen and paracetamol both activating the bacteria’s defences to expel antibiotics and render them less effective.”
The study examined nine medications frequently prescribed in residential aged care: ibuprofen (anti-inflammatory pain relief), diclofenac (anti-inflammatory for arthritis), acetaminophen/paracetamol (for pain and fever), furosemide (for high blood pressure), metformin (for diabetes-related high blood sugar), atorvastatin (to reduce cholesterol and blood fats), tramadol (a stronger pain reliever often used after surgery), temazepam (for sleep disorders), and pseudoephedrine (a decongestant).
Associate Professor Venter explains that the findings reveal antibiotic resistance is far more complex than once thought, with everyday non-antibiotic drugs also contributing to the problem.
“Antibiotic resistance isn’t just about antibiotics anymore,” Assoc Prof Venter says.
“This study is a clear reminder that we need to carefully consider the risks of using multiple medications — particularly in aged care where residents are often prescribed a mix of long-term treatments.
“This doesn’t mean we should stop using these medications, but we do need to be more mindful about how they interact with antibiotics — and that includes looking beyond just two-drug combinations.”
The team of scientists is advocating that additional studies be carried out on drug interactions among any set of individuals on long-term medication treatment regimes to enable a greater understanding of how common drugs are likely to affect antibiotic effectiveness.
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