The drug thins the blood and is commonly prescribed to help prevent heart attacks and strokes in people at high risk - it works by improving circulation, preventing clots and reducing inflammation.
It is thought to help with erectile dysfunction by increasing blood flow to the penis.
And, similar to Viagra, aspirin may also increase levels of nitric oxide, a gas that widens blood vessels and, in turn, improves blood flow.
This is thought to be the first study to assess how aspirin could help men with impotence.
It is estimated that erectile dysfunction - defined as the inability to have an erection that is satisfactory for sexual intercourse - affects about 40% of men aged 40 at some point; by 70, it’s 70%.
Although stress and other psychological and social factors can be involved, in 90% of cases the cause is vascular problems, where not enough blood gets to the penis.
A healthy blood supply is crucial for creating and maintaining an erection. This occurs when the arteries relax and open up to let more blood flow in and the veins close. Once blood is in the penis, pressure traps it.
However, if the blood vessels in this area narrow - usually due to ageing, or because they become furred up with fatty deposits - it can significantly reduce blood flow in the penile tissue.
Lifestyle changes, such as losing weight, exercise, not smoking and reducing alcohol consumption, can help. Medications including Viagra, Cialis or Levitra - which all work by dilating the arteries that supply the penis - are also an option.
But these drugs can have side-effects - for example, headaches and visual disturbances - and are not effective for everyone. These medications are unsuitable for men with angina, for instance. They also have to be taken well in advance of sexual intercourse to allow effective concentrations of the drug to be reached.
In the new study, by Istanbul Medipol University in Turkey, doctors looked at the effects of low-dose aspirin - 100mg, roughly the amount prescribed to patients at risk of heart attacks and stroke - compared to a placebo.
About 200 men aged between 18 and 76 with erectile dysfunction were given either aspirin or placebo pills to take once daily for six weeks. Questionnaires were given to them before and after the trial period.
Results published last month in the journal International Urology and Nephrology showed that the proportion of men who were able to sustain an erection for intercourse increased from 31% to 78% in the aspirin group.
There was no significant change in those who took a placebo. Professor Raj Persad, a consultant urologist with Bristol Urology Associates, says: “If these results are confirmed in larger trials, aspirin could be a very effective and inexpensive treatment for erectile dysfunction.”
However, he warns that just because aspirin is a common over-the-counter drug doesn’t mean it is suitable for everyone.
“We should always be mindful of the fact that in some patients and the elderly, even one aspirin can cause severe gastrointestinal upset or bleeding,” he says.
Elsewhere, researchers are investigating a more high-tech approach to the problem.
A new shock-wave treatment for impotence has been found to have benefits that can last for at least two years.
The therapy involves using a probe to apply low-intensity shockwaves to the penis for about 20 minutes. Men usually don’t need anaesthesia or experience pain, although they might have a tingling sensation.
Research in the Journal of Urology shows that the initial success rate was 63.5%, dropping to 53.5% after two years.