Aspirin is a bad bargain for healthy women trying to stave off heart attacks or strokes, although it's commonly used for that purpose, Dutch researchers say.

In a new report, they say 50 women will need to take the medication for 10 years for just one to be helped - and that's assuming they are at high risk to begin with.

"There are very few women who actually benefit," says Dr Jannick Dorresteijn of University Medical Center Utrecht in The Netherlands.

"If you don't want to treat 49 patients for nothing to benefit one, you shouldn't treat anyone with aspirin."

The new study adds to a longstanding controversy over aspirin, one of the world's most widely used drugs. Doctors agree it's worth taking for people who've already had a heart attack or a stroke, but they are less certain when it comes to so-called primary prevention.