Excerpt: THE smell of rotting eggs gives men an erection.
And the bizarre finding could help doctors to develop a more effective version of the sex drug Viagra, boffins say.
A gas called hydrogen sulphide – also released when eggs rot and from the exhausts of cars with catalytic converters – is given out by men just before they have sex.
Tiny amounts of it are released by nerve cells in a man's private part to prepare it for intercourse, a study found.
The gas causes muscle cells in the region to relax, boosting blood flow, and leading to a better erection.
Viagra, however, harnesses a different chemical – nitric oxide – to give users a boost.
But one third of men have found the drug ineffective.
The discovery could now help to improve the sex lives of countless men.
Researchers, from the University of Naples in Italy, made the finding in a study of eight men who had sex-change ops....