Australian researchers have found regular users may increase their risk of age-related macular degeneration.
Aspirin is the age-old drug that's been trusted by families for generations. It's prescribed by doctors for headaches and to thin out blood to prevent clots and heart attacks.
But now a national study by Sydney's Westmead Millennium Institute claims aspirin might actually be harmful.More stories from Today Tonight
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An important new discovery about a risk factor that hadn't been considered before has linked aspirin to macular degeneration - the biggest cause of blindness in Australia.
Macular degeneration is a disease of the retina, resulting in loss of central vision. Smoking and family history are both contributing factors, and now aspirin seems to be another.
Professor Paul Mitchell specialises in the disease and found the vital link between aspirin and the eye disease.
"We looked over a period to see if the use of medication, in particular aspirin in this case, whether it was associated with a greater long-term risk of the condition," Professor Mitchell said.
"We were quite surprised by the findings because in the original cross-section analysis of data, back when we started the project, we looked at a whole range of medications to see whether they were important, and we didn't really find an association."
The fifteen year study examined the eyesight of 2389 people over the age of 50.
"We invited them to come back every five years. We examined their eyes, we took photographs of the back of the eyes and documented exactly from the photographs where the macular degeneration had developed," Professor Mitchell said.
The study discovered that those who were regular users of aspirin, taking it at least once a week, were two and a half times more likely to suffer from macular degeneration.
"We found that of the people we followed, about 9.3 per cent of those on aspirin developed this condition - wet macular degeneration, whereas only 3.7 per cent who weren't taking aspirin developed it," Professor Mitchell said.
52-year-old Ann Keegan had a heart attack five years ago. With a strong family history of heart disease she was prescribed aspirin from her doctor to help thin the blood and prevent blood clots.
She vows she won't stop taking the medicine.
"It is early days with the study and I will just wait and see. I would rather have my heart working properly at the moment," Keegan said.
"There are pros and cons for taking things and not taking things, so you just have to see what works for you the best."
40 thousand tonnes of aspirin is consumed each year worldwide, making it one of the most popular forms of medication.
Julie-Anne Mitchell from the Heart Foundation says the benefits of aspirin far outweigh the risks.
"It's been used for a long time and the evidence is strong that for those with heart disease, a small amount taken daily will reduce their risk of a second heart attack or stroke," Mitchell said.
As for the report, Professor Mitchell says there is still more evidence and research needed before any changes to clinical practice are considered.
This reporter is on Twitter at @maddykennard