Methotrexate is a drug taken, often over long periods of time, to limit or prevent joint damage and disability.
People who take methotrexate are often advised to abstain from alcohol as both methotrexate and alcohol are known to increase the risks of liver damage.
However, it is not known whether drinking modest amounts of alcohol is safe during methotrexate therapy.
The new study by The University of Manchester has looked at the medical records of almost 12,000 people with rheumatoid arthritis taking the drug who had a record of the levels of alcohol they drank and who had routine blood monitoring test results.
The researchers found that increased use of alcohol did indeed correspond to increased liver damage, but at 14 units or fewer there was no heightened risk.
“We know that methotrexate can be an effective drug for treating arthritis,” said Dr Natalie Carter, head of Research Liaison and Evaluation at Arthritis Research UK.
“As it can interact with other medicines and alcohol it is important that people with arthritis have information about their medication in order to manage their arthritis safely and effectively.
“Arthritis Research UK invests in exceptional science to find treatments and information that let people push back the limits these conditions cause.
“This research adds to the knowledge we have around methotrexate and its effects in people with rheumatoid arthritis, which can help people make informed decisions about their treatment.