Paracetamol, also known as acetaminophen in the US, stands as the most commonly utilized painkiller globally, frequently taken for a range of ailments from headaches and fevers to back pain. With an average Briton consuming approximately 70 tablets annually, and the NHS in England issuing over 15 million prescriptions in 2024/25 at a cost of £80.6 million, its pervasive use is undeniable. However, growing concerns, supported by recent studies, challenge the long-held belief in its inherent safety, particularly with regular use.

A consensus among medical professionals, including Professor Andrew Moore from the respected Cochrane Collaboration’s Pain, Palliative Care and Supportive Care group, suggests that the conventional view of paracetamol as a safe, 'go-to' pain treatment is likely incorrect. Studies indicate associations between paracetamol use and increased rates of death, heart attack, stomach bleeding, and kidney failure. While acute liver failure in overdose is well-known, even standard doses can pose a risk, estimated at about one in a million, contributing to a stacking effect of various health risks.

GPs, such as Dr. Dean Eggitt, echo these warnings, cautioning against the public perception of paracetamol as harmless due to its easy accessibility. Even without exceeding the recommended daily dose of 4g (equivalent to two 500mg tablets four times a day), prolonged use can lead to serious complications. Dr. Eggitt warns that slightly exceeding this dose daily for ten or more days could cause permanent liver and kidney damage.

The mechanism of paracetamol-induced liver damage involves its breakdown into a toxic by-product called NAPQI. While the body's protective substance, glutathione, can neutralize NAPQI at low doses, high doses or chronic use can overwhelm the liver, depleting glutathione stores and leading to damage. This risk is amplified in individuals who are underweight, consume alcohol, or have pre-existing liver disease. Furthermore, accidental overdoses can occur unknowingly, as paracetamol is an active ingredient in various soluble cold remedies like Lemsip or Beechams.

Beyond safety concerns, the efficacy of paracetamol for pain relief is also under scrutiny. Reviews of evidence suggest it may not be as effective as commonly believed, especially for chronic conditions. For instance, Professor Moore notes that perhaps only one in four people benefit from it for postoperative pain, and one in ten for headaches. The UK’s medicines watchdog, NICE, revised its guidelines in 2020, advising against the use of paracetamol for chronic pain due to a lack of evidence of its effectiveness and the potential for harm, including liver toxicity, kidney damage, and gastrointestinal issues with regular intake. Studies specifically on lower back pain and osteoarthritis found paracetamol to be “no better than placebo” and ineffective in improving quality of life.

Historically considered a safer alternative to non-steroidal anti-inflammatory drugs (NSAIDs) for conditions like high blood pressure, paracetamol itself may pose similar cardiovascular risks. Multiple studies indicate that paracetamol can elevate blood pressure. A 2022 University of Edinburgh study observed a noticeable rise in blood pressure among patients with a history of hypertension after taking the standard paracetamol dose for two weeks. A large US study also linked chronic paracetamol use to a doubled risk of high blood pressure in women, which increases the likelihood of heart attacks and strokes over time. Professor Weiya Zhang of the University of Nottingham suggests that paracetamol might target similar pain receptors as NSAIDs, potentially explaining this effect. Despite this, paracetamol is still recommended for short-term pain in individuals with high blood pressure, though NHS and NICE guidelines advise the lowest effective dose for the shortest duration for those with cardiovascular problems.

Other emerging concerns include a potential link to tinnitus, a condition characterized by a ringing or buzzing in the ears. A recent US observational study found that a daily dose of paracetamol was associated with an 18 percent increased risk of developing tinnitus. While this study did not prove causation and acknowledged other factors could be at play, previous research has indicated that painkillers, particularly NSAIDs, can damage the inner ear. Healthcare professionals advise consultation before regular use of over-the-counter painkillers, especially if considering long-term regimens.

There is also emerging data suggesting an association between paracetamol use during pregnancy and an increased risk of autism and ADHD in children. An analysis of 100,000 individuals by researchers from Harvard’s School of Public Health and Mount Sinai Hospital indicated that mothers exposed to paracetamol during pregnancy were more likely to have children with these developmental disorders. However, this remains an observational finding, lacking definitive proof of causation, and further research is needed to exclude other potential risk factors.

A major study tracking half a million individuals over 65 for two decades revealed significant risks for older adults prescribed paracetamol by their GP. Even those prescribed the painkiller twice in six months faced an increased risk of gastrointestinal bleeding, chronic kidney disease, stomach ulcers, heart failure, and hypertension. Those with the highest usage were more prone to severe outcomes like burst stomach ulcers or significant bleeding. Professor Zhang emphasizes that for all users, particularly those over 65, the message from these studies is clear: take the lowest effective dose only as needed, and avoid continuous use, especially at the maximum therapeutic dose, to mitigate potential problems.