Testosterone is the only agent known to improve desire and arousal in women, reports News.com.au.
"Women who used the patch experienced twice the number of satisfactory events than women using a placebo patch. That's an exciting development given no other agent has been found to help women," said the lead investigator Professor Susan Davis, from Monash University in Melbourne.
For the study, the researchers studied 814 post-menopausal women worldwide who were given either the male hormone or a dummy patch, which is stuck to the stomach and was changed twice weekly.
Developed by US drug company Procter and Gamble, the patch is not yet available in Australia.
Before the study, the women enjoyed half their sexual encounters. However, after six months, those on the testosterone patch had an extra two satisfying experiences a month, in contrast with 0.7 among the placebo group.
"We already knew it could work among women taking oestrogen as part of hormone replacement therapy (HRT), but HRT isn't for everyone so it's important to know it works alone too," said Davis.
She also said that there was a "nervousness" among women in using a male hormone, "but women actually have more testosterone in their blood at any given time than oestrogen".
However, the testosterone boost did bring masculinising side effects-a modest increase in unwanted body hair, but no change in voice pitch.
According to sexual health specialist Professor Basil Donovan, of the University of Sydney, it was possible that the side effects could worsen with time, but the results were promising overall.
"I don't think they'll get the same market as (the male anti-impotence drug) Viagra, but it may help many long-term relationships," said Donovan.
He added: "For a lot of women, the flower of their sexual career is often in their post-menopausal years when they're no longer busy with work and have met the man they want to be with, and this may be just what they need."
He further claimed that younger women who are androgen deficit may also benefit from the patch.
For a natural boost to the sex drive, the researchers recommended general improvements to health through a better diet, more exercise, less alcohol and fewer life stresses.
The study was published in the New England Journal of Medicine.