A painkiller taken by millions may protect against Parkinson's and even slow progression of the disease, research suggests.
Findings from a large study in the US showed that ibuprofen, widely marketed in Ireland as Nurofen, lowered the risk of developing Parkinson's disease by as much as 38pc.
Other pain-relieving medicines, such as aspirin, naproxen and diclofenac, did not have the same effect.
Researchers believe ibuprofen may have a unique ability to protect the brain cells that are lost by Parkinson's patients.
But experts warn that excessive use of ibuprofen can lead to harmful side effects, such as gastro-intestinal bleeding.
The scientists analysed data from more than 37,000 male health professionals and almost 99,000 female nurses.
Over a six-year period, 156 men and 135 women were diagnosed with Parkinson's disease.
Participants' use of medicines known as Non-Steroidal Anti-Inflammatory Drugs (NSAIDS) was recorded along with other information such as age, smoking habits, and diet. The results showed that those who took ibuprofen two or more times a week were 38pc less likely to develop Parkinson's.
Dr Xiang Gao, from the Harvard School of Public Health in Boston, Massachusetts, said: "Our findings suggest that ibuprofen could be a potential neuroprotective agent against Parkinson's disease, however the exact mechanism is unknown.