Giving hip or knee replacement patients a clotting drug may reduce the need for a blood transfusion during surgery, experts say.

Patients undergoing hip or knee replacement surgery could benefit from taking a clotting drug before their operation, new research suggests.

Giving patients tranexamic acid can reduce the need for a blood transfusion while not increasing the risk of complications, experts found.

The drug has been linked to a reduction of blood loss during surgery but concerns have been raised over the safety of taking the medication.

A team of US researchers examined data concerning almost 900,000 patients having hip or knee replacements at 510 US hospitals between 2006 and 2012.

Their study, published on thebmj.com, found that the use of tranexamic acid was associated with a 69 per cent reduction for the need of blood transfusions and was not associated with an increased risk in complications.

However in an accompanying editorial, experts from the London School of Hygiene and Tropical Medicine said it would be "premature to recommend the routine use of tranexamic acid in general and orthopaedic surgery".

They pointed out ambiguities over the risk of complications - for instance post-op heart attacks often go undetected - and called for a separate trial to resolve the uncertainties.