Millions of patients may be taking drug combinations that raise the risk of potentially fatal complications, including serious organ damage, experts have warned.
Using a statin alongside anti-inflammatory painkillers is common in Britain, with the pain medicines often prescribed to manage side effects linked to heart medication.
But pharmacists say taking the two types of medicine together over a number of years can sharply increase the danger of severe stomach bleeding and kidney damage.
Canadian researchers have now listed this combination among 24 common drug “cocktails” that may expose patients to preventable side effects and complications.
Such prescribing cascades can do more than contribute to long-term harm. When one medicine is used to counter the side effects of another, the original cause of a patient’s symptoms may go unchecked.
Other commonly used combinations considered potentially risky include iron supplements taken with laxatives, and cholinesterase inhibitors for dementia symptoms used alongside sleeping tablets.
Laxatives prescribed for medication-related constipation can trigger diarrhoea and potentially dangerous chemical imbalances. Sleeping pills, meanwhile, have been associated with a higher risk of falls and hospital admission among older people.
The University of Toronto researchers found that older women were more likely than other groups to receive potentially harmful medication combinations.
Researchers found that certain drug combinations can trap patients in a cycle of prescriptions
‘These sequences of events are common but often missed in clinical practice,’ warned Dr Paula Rochon, a geriatrician at the O’Born Centre for Mature Women’s Health and the study’s first author.
‘Knowing which medicines you take, when they were started and why they were prescribed is essential for identifying prescribing cascades that could cause harm.’
Research suggests that more than one in seven people in England take at least five prescription medicines every day.
Most are older patients, who are more likely to be living with several long-term health conditions and therefore need multiple treatments.
The new research examined how often prescribing cascades occur across Ontario’s general population in Canada.
The researchers began by reviewing 65 medication patterns that experts believed could put patients at risk.
They then analysed prescription records held by Ontario’s health data institute to determine which of these cascades occurred most frequently in everyday clinical practice.
This analysis identified 24 common prescribing patterns that were considered potentially harmful.
The public has previously been warned about relying too heavily on anti-inflammatory painkillers such as ibuprofen, which can affect kidney function
Writing in the British Medical Journal, the researchers said the most widespread pattern involved iron supplements such as ferrous fumarate, which can cause constipation.
Rather than reassessing the initial treatment, about one in 10 patients were given a laxative to relieve the resulting side effect.
Another frequently observed pattern involved statins.
Patients prescribed the cholesterol-lowering drugs were then often given painkillers called non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, to help ease aches and pains, rather than adjusting statin doses.
‘Statins can cause a side effect known as statin-associated myalgia which can present as muscle aches,’ said Ian Budd, Lead Prescribing Pharmacist at Chemist4U.
‘This condition is potentially serious if not recognised for what it is.
‘Meanwhile, long term use of NSAIDs like ibuprofen may expose patients to gastrointestinal bleeding, kidney injury, and cardiovascular complications.’
The findings come amid growing efforts within the NHS to tackle problematic polypharmacy, with doctors increasingly encouraged to review whether long-term medicines remain necessary and, where appropriate, reduce medicines whose risks outweigh their benefits.
A government-led review published in 2021, which found that a tenth of prescription medicines doled out by GPs are unnecessary, called for regular checks of patients’ medicines.
Around one in five hospital admissions among those over the age of 65 were also found to be caused by adverse effects of medicines.
When clinicians were asked what was driving prescribing cascades, many said they lacked sufficient time to fully investigate the cause of new symptoms.
Others said they felt they had no other option but to prescribe pills because the waiting lists for other treatments were too long.
The team hope that automated clinical decision support systems will help flag these cascades in real time, prevent errors and ensure clinicians can access more details about previously prescribed medications.
They added that pharmacists could also help alleviate the burden, by helping to identify these potentially inappropriate prescribing patterns before patients are exposed to further risk.
Patients should not stop taking prescribed medications without advice from a healthcare professional.
