Even really low doses of paracetamol could damage your heart, scientists discover

LOW doses of paracetamol that are “considered safe” can alter your heart, a study shows.

The painkiller — also known as acetaminophen — changed proteins in the heart tissue of mice, US researchers found.

AlamyK67J1E Pain killers: open blister pack of paracetamol pills or tablets with two paracetamol 500 mg caplets removed.[/caption]

Dr Gabriela Rivera, of the University of California, Davis, said: “We found that regular use of acetaminophen at concentrations that are considered safe — equivalent to 500 mg/day — causes numerous signalling pathways inside the heart to be altered. 

“We expected two to three pathways to be altered, but we found over 20 different signalling pathways being affected.

“These results prompt me to consider using acetaminophen at the lowest effective dose and for the shortest duration possible.”

Paracetamol is one of the most commonly taken drugs in the UK, with the average Brit having 70 tablets a year.

The painkiller is normally considered safe but it is the most common drug taken in overdose in the UK, with around 100,000 people presenting to emergency departments every year.

Previous research has suggested taking it in large quantities can cause heart problems.

The latest study, presented at the American Physiology Summit in Long Beach, California, looked at the effects it can have at other doses.

Researchers gave a group of mice plain water, while others were given water containing the equivalent of 500 mg per day of paracetamol in an adult human.

They then analysed their heart tissues to see how the proteins changed — an indicator of how well the organ is working.

After seven days, the mice given paracetamol showed significant changes in the levels of proteins associated with biochemical pathways involved in a range of functions.

These included energy production, antioxidant usage and the breakdown of damaged proteins, the researchers said.

Long-term medium- to high-dose use could cause heart issues as a result of oxidative stress or the buildup of toxins that are produced as paracetamol breaks down, they added. 

While our bodies can usually clear such toxins before they cause damage, it may be harder for the body to keep up when medium- to high- doses are taken consistently over time, Dr Rivera said.

But she said the study was on mice and further research on humans is needed.