As with any type of drug, taking too much paracetamol can be dangerous. All pain relievers, prescription or over-the-counter medications carry potential risks, especially when taken in high doses or over a long period of time. With paracetamol, one of the main problems is that overdoses of the painkiller can cause liver damage, which can be fatal and difficult to treat.
A 2017 study by scientists at the University of Edinburgh revealed the possible effects of paracetamol on liver cells. Studies have found that in some cases paracetamol can damage important structural connections between adjacent cells in the liver.
Acetaminophen overdose is the leading cause of liver failure in the United States — about 46 percent of all causes, with a 30 percent mortality rate. In 2015, health authorities in Australia and New Zealand raised concerns about a large number of children, mostly aged five and under, developing acute liver failure after taking paracetamol.
In a 2015 study published in the British Medical Journal, British researchers also found that long-term users of acetaminophen — people who typically take large daily doses over several years — may have an increased risk of death or kidney complications, bowel and heart problems.
The review included eight cohort studies from the United States, United Kingdom, Sweden and Denmark.
Two of the eight studies found that long-term paracetamol use increased the risk of death by as much as 63 percent. One study reported that the risk of gastrointestinal bleeding and other intestinal side effects was up to 36%.
In 2011, a similar study by Professor Michael Doherty looked at nearly 900 patients aged 40 and older who took paracetamol, ibuprofen, or a combination of both to treat chronic knee pain. After 13 weeks, one fifth of those taking paracetamol had internal bleeding.
Long-term use of paracetamol can also lead to heart problems. A systematic review of eight observational studies found an increased risk of cardiovascular problems in four of them, ranging from 19% to 68%. Higher doses of paracetamol have also been linked to heart attacks and strokes, according to another study.
Systematic reviews also linked long-term use of acetaminophen to an increased risk of impaired kidney function. Four studies revealed renal effects, while three found increased doses led to poorer renal function. An analysis of all eight cohort studies showed that in all cases the risk was dose-dependent – the higher the dose, the greater the risk.
