Ibuprofen and paracetamol feel so safe and ordinary that few people think twice before swallowing a couple of tablets. New research suggests that this casual habit, when mixed with antibiotics, could quietly be helping to fuel one of the biggest health threats of the century.
From handy helpers to hidden health risk
In France they are known by brand names like Doliprane and Advil; in the UK and US, paracetamol (or acetaminophen) and ibuprofen are the go‑to answers for headaches, period pain, fever and minor injuries. They are cheap, widely available, and in most cases, effective.
That huge popularity is part of the problem. Many people take them frequently, and sometimes chronically, often alongside other drugs. Until recently, most concerns around these pills focused on liver damage from paracetamol overdoses or stomach and kidney issues from ibuprofen.
Researchers in Australia are now raising a different kind of alarm: not about what these painkillers do to our own organs, but about what they do to bacteria when taken with antibiotics.
Ordinary painkillers, when combined with antibiotics, can help bacteria learn how to fight back against the very drugs designed to kill them.
What the new study actually found
A team at the University of South Australia, publishing in the journal Nature in August 2025, investigated how a familiar bacterium, Escherichia coli (E. coli), reacts when exposed to both a painkiller and ciprofloxacin, a widely used antibiotic.
E. coli is best known for causing urinary tract infections and some forms of food poisoning. Doctors rely on antibiotics like ciprofloxacin to keep such infections under control.
Bacteria naturally evolve resistance when repeatedly exposed to antibiotics, especially at low or incomplete doses. That much is well known. The Australian team wanted to see whether adding common painkillers into the mix would change the speed or pattern of that resistance.
They observed that E. coli exposed to both an antibiotic and an over‑the‑counter painkiller developed stronger and broader resistance than bacteria treated with the antibiotic alone. The microbes did not just adapt to ciprofloxacin, but became harder to kill with other antibiotics as well.
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When painkillers sat alongside antibiotics, E. coli became tougher, faster – and not only against one drug, but several.
Why this matters beyond the lab
In real life, that scenario is extremely common. A patient with a urinary tract infection, a child with an ear infection, or an adult with pneumonia is routinely prescribed antibiotics and told they can also take ibuprofen or paracetamol to manage fever and pain.
For now, doctors still say there is a place for that combination. Severe infections hurt. Without pain relief, many patients would struggle to function, and some would simply stop taking their antibiotics out of discomfort, which also promotes resistance.
The new data does not mean everyone should suddenly stop using painkillers. It does suggest that the overall effect of such combinations on bacterial evolution has been underestimated for years.
Antibiotic resistance: the slow-moving global crisis
Antibiotic resistance is already killing large numbers of people. The World Health Organization estimates that antimicrobial resistance, which includes antibiotic resistance, was directly linked to 1.27 million deaths worldwide in 2019. That figure is expected to rise sharply if current trends continue.
When bacteria become resistant, standard drugs no longer work. Infections that used to be routine to treat can drag on, spread, and sometimes turn deadly. Operations, chemotherapy and intensive care all rely on antibiotics working reliably in the background.
Experts warn of a future where a simple cut or bladder infection could again carry fatal risk because antibiotics no longer do the job.
If painkillers are quietly nudging bacteria toward resistance each time they are taken with antibiotics, that future could arrive faster than predicted.
Who faces the highest risk?
Some groups are far more exposed to this problem than others:
- Older adults, who often take multiple medicines at the same time for chronic conditions.
- People with long-term illnesses, such as diabetes or cancer, who frequently need repeated courses of antibiotics.
- Hospital patients, especially in intensive care, where powerful antibiotics and regular pain relief are standard.
- Children, who commonly receive antibiotics and painkillers together for ear, throat or chest infections.
In these settings, small, repeated boosts to bacterial resistance can add up over months and years, making once-reliable drugs steadily less effective.
Should we stop taking ibuprofen and paracetamol?
Researchers and clinicians are not calling for a ban on these medicines. Used correctly, they remain valuable tools for controlling pain and fever.
Paracetamol, for instance, is still the first-line option for many types of mild to moderate pain and can be safer for the stomach than ibuprofen. Ibuprofen, an anti-inflammatory, can be helpful where swelling plays a role, such as in sprains or some types of joint pain.
The message from the Australian team, and from infectious disease experts, is more about how and when we combine these drugs with antibiotics.
Pain relief still matters, but the casual, automatic pairing of “antibiotic plus something for the pain” needs a second look.
Smarter ways to use everyday painkillers
Several practical steps can reduce unnecessary risks without leaving people in pain. Health professionals point to a few simple changes:
| Practice | Why it helps |
|---|---|
| Ask if an antibiotic is truly needed | Many viral infections do not benefit from antibiotics, cutting out the risky combination entirely. |
| Limit duration of combined use | Use painkillers for the shortest period that keeps symptoms tolerable while on antibiotics. |
| Avoid “just in case” dosing | Do not take ibuprofen or paracetamol around the clock if pain or fever has already eased. |
| Review medicine lists for older people | Regular checks help remove unnecessary painkillers and reduce constant drug pressure on bacteria. |
| Follow dosage guidelines strictly | Sticking to recommended doses avoids extra stress on the body and on bacterial populations. |
What might be happening inside the bacteria
The study focused on outcomes rather than the finer details of bacterial biology, but scientists have some working theories. When bacteria face both an antibiotic and another drug, such as a painkiller, they experience extra stress.
Under stress, microbes often switch on genes that help them survive. These can include pumps that push drugs out of the bacterial cell, changes in the cell wall, or faster mutation rates. Over time, these adaptations can make them tougher across a range of antibiotics, not just one.
Painkillers may also affect how antibiotics travel through the body or how they reach bacteria, changing the effective dose microbes experience. That kind of “scattered pressure” can provide further opportunities for partial survival and adaptation.
What this means for everyday choices
Imagine two parallel versions of the same winter:
In the first, people routinely ask for antibiotics at the first sign of a cold, then add ibuprofen or paracetamol “just in case” of discomfort. Bacteria in their bodies meet that pairing again and again, quietly upgrading their defences each time.
In the second, antibiotics are used more sparingly, reserved for clear bacterial infections. When they are prescribed, painkillers are used only for as long as symptoms remain genuinely bothersome. Bacteria get far fewer chances to practise resisting both drugs together.
On an individual level, the difference between those two winters might feel small. On a global scale, repeated year after year, the gap in resistance levels could be dramatic.
For people who live with chronic pain, the idea of cutting back on pills can sound unrealistic. This is where tailored pain plans, physiotherapy, psychological support and non-drug approaches start to matter. Each tablet that can safely be avoided during an antibiotic course is one less nudge toward tougher bacteria.
Terms like “antimicrobial resistance” and “drug interactions” can sound abstract, but they now touch some of the most ordinary actions in daily life: reaching for a pack of paracetamol, asking a GP for antibiotics, or buying ibuprofen at the supermarket. The new research suggests those moments deserve a little more thought than they usually get.