Scientists have warned older adults not to take acetaminophen regularly because of its association with alarming conditions such as internal bleeding and chronic kidney disease.
An important analysis carried out by experts at the University of Nottingham has found a “dose-dependent” relationship between the use of the painkiller and digestive, heart and kidney problems.
The study, which followed the health of more than half a million people over 65 for 20 years, revealed that those prescribed paracetamol twice in six months were at particularly high risk of complications.
Compared with a group of age-matched controls, those with this number of prescriptions were more likely to suffer from stomach ulcers, heart failure, hypertension and chronic kidney disease.
The more paracetamol a person used, the more likely they were to see a stomach ulcer bleed or open.
The pain reliever is often prescribed to older people to help manage the symptoms of a variety of chronic diseases such as arthritis and osteoporosis.
Studies suggest About 90 percent of people over 75 years old regularly take paracetamol, mainly to treat joint and bone pain, as well as the consequences of falls.
But the author of the new study, Professor Weiya Zhang, an epidemiologist at the Biomedical Research Center at the National Institute for Health and Care Research at the University of Nottingham, said patients should “carefully consider” whether or not to take the drug with frequency.
Paracetamol, known as acetaminophen in the United States, is one of the most common medications worldwide.
“The use of paracetamol as a first-line analgesic for chronic conditions such as osteoarthritis in older people should be carefully considered,” he said, adding that evidence shows it has a “minimal pain-relieving effect.”
In 2022, the National Institute for Health and Care Excellence changed its guidelines for the treatment of osteoarthritis, the type of age-related disease that develops when protective cartilage at the ends of the bones break, causing pain and mobility problems.
The updated rules state that GPs should offer exercise programs as a first-line treatment for the condition and avoid “routinely” offering paracetamol as it is unlikely to be effective.
Anti-inflammatory creams can be used “in conjunction” with exercise, the guide adds.
Paracetamol has long been thought to be gentler on the gut than non-steroidal anti-inflammatory painkillers such as ibuprofen.
However, some studies suggest that, in high doses, it can cause irritation in the upper gastrointestinal tract, causing symptoms such as heartburn, pain, nausea and vomiting.
Previous research has shown that too much acetaminophen can increase blood pressure. This graph shows the average increase in blood pressure observed at various points among participants when they took a daily paracetamol dose of 4 g of paracetamol.
Currently, scientists are not sure why the drug may cause kidney problems; However, some studies have suggested that it could interact with chemicals in the body to form toxins that damage cells in the organ.
Experts have long warned about the impact of high doses of the painkiller on the liver.
Excessive doses of the drug (sold as Tylenol in the US) are considered the leading cause of acute liver failure in the Western world.
Too much overwhelms the liver’s normal pathway to safely metabolize the drug and instead ends up in a toxic form that damages cells and eventually leads to liver failure.
A 2017 study found that the type of damage to organ cells caused by acetaminophen is similar to that induced by alcohol and hepatitis.
Meanwhile, other studies have found links between long-term use of the painkiller and high blood pressure.
This is thought to be due to the fact that many patients take soluble versions of the medication, which is high in sodium, increasing the risk of blood pressure spikes.
The maximum safe dose of paracetamol for adults is two 500 mg tablets or capsules four times a day.
The NHS advises that no more than eight tablets should be taken in a 24-hour period.
Experts have previously warned that it is “too easy” to overdose on painkillers, as many people combine different paracetamol-containing products, such as those that treat cold and flu, and lose track of the dosage.
Dr Kenneth Simpson, a specialist in liver diseases at the University of Edinburgh, previously told MailOnline that staggered overdoses can occur when people are in pain and repeatedly take slightly more paracetamol than they should.
He said: “They have not suffered the kind of massive overdoses that people attempting suicide suffer, but over time the damage accumulates and the effect can be fatal.”
“They often take paracetamol for pain and don’t keep track of how much they have consumed for a few days.”