Doctors may be under-estimating the risks
to patients from long-term use of paracetamol, the world's most popular
painkiller, researchers said Tuesday.
Chronic users of the drug -- people who
typically take large, daily doses over several years -- may increase
their risk of death, or kidney, intestinal and heart problems, they
found.
Led by Philip Conaghan at the Leeds
Institute of Rheumatic and Musculoskeletal Medicine in northern England,
the team analysed data from eight previously-published studies into
long-term paracetamol use.
The data came only from people who had paracetamol prescribed by a doctor, as opposed to over-the-counter purchases.
Two of the eight studies had found an
increased risk of mortality, up to 63 percent, among long-term
paracetamol users, compared to those who had not been prescribed the
drug during the study period.
Four found a heightened risk, ranging
from 19 to 68 percent, of cardiovascular problems. The risk of
gastro-intestinal bleeding and other intestinal side-effects was up to
49 percent as high.
Three studies found an adverse effect on kidneys.
In all cases, the risk was dose-dependent
-- in other words, the higher the dose, the greater the risk, said the
analysis published in the British journal Annals of the Rheumatic
Diseases.
Even though the risk in absolute terms was small, doctors should think carefully when prescribing the drug, it warned.
"We believe the true risk of paracetamol
prescription to be higher than that currently perceived in the clinical
community," said the report.
"(...) A systemic review of paracetamol's efficacy and tolerability in individual conditions is warranted."
Other experts cautioned against over-reaction.
They pointed out the analysis was unable
to tell whether early death and health problems were caused by an
underlying illness rather than from the paracetamol.
Nor did it take into account over-the-counter purchases of the drug, a picture that could be far more complex.
"Paracetamol remains the safest analgesic
(painkiller) available, and this study should not stop people taking
it," said Nick Bateman, a professor of clinical toxicology at the
University of Edinburgh in Scotland.
"Based on these results, the lowest
effective dose for the shortest necessary period is advised," he told
Britain's Science Media Centre. "This is common sense for all
medicines."
Seif Shaheen, a respiratory epidemiology
professor at London's Queen Mary University, said the review, given its
limitations, did nothing to strengthen the evidence for paracetamol's
harmful effects.
"However, further rigorous research into possible detrimental effects of this commonly used drug would be prudent."
Widely recommended as the first rung on
the painkilling ladder, paracetamol is considered by many to be safer
than aspirin and ibuprofen.
The new study pointed to other research
findings that paracetamol may have no painkilling advantage over rivals
when it comes to treating osteoarthritis, joint pain or acute lower-back
pain.
In this light, "more careful consideration of its usage is required," the paper said.
"Prescribers need to be aware of
patients' individual responses to paracetamol and the observed increased
toxicity with regular and higher dosing."
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