Sun, 08 Apr 2012 14:54 UTC
But oxytocin, the so-called 'cuddle hormone', can dramatically improve male sexual performance, researchers have found - producing results on a par with Viagra.
One of the scientists behind the discovery and development of Viagra was so impressed that he described an oxytocin-based treatment as having 'blockbuster potential'.
Oxytocin is a hormone naturally made in the body in both men and women, and is involved in sex, sexual attraction, trust and confidence.
Extra doses of the 'cuddle chemical' are released into a mother's blood during labour - triggering the production of breast milk - and flood the brain during breastfeeding, helping mother and baby bond.
It has recently been shown to make men more sensitive and in tune with others' feelings, but its effects on the male physique were unknown until now.
Researchers in California published a paper on the hormone's effects after giving it to a married father of three who suffered from attention deficit disorder and had difficulty in maintaining social relationships.
Research found that a married man who sniffed the spray twice a day saw a considerable improvement in his sexual performance
His relationship with his wife was also in difficulties, and conventional drugs either were not suitable or had unwanted side-effects.
Spraying the hormone up his nose twice a day did little to help his social phobia but did wonders for his love life, the Journal of Sexual Medicine reports.
His libido went from 'very weak' to 'somewhat strong', his sexual arousal from 'somewhat difficult' to 'somewhat easy' and the act itself was easier to perform and more satisfying.
The spray also produced emotional benefits. The man said he found it easier to be affectionate towards his wife, while she said he wanted to be closer to her and was more tactile.
But not all its effects may be quite so welcome.
The man, who is identified only as Mr B, also hugged a work colleague in a 'very out of character' way. At the time the paper was written, the man had not experienced any other side-effects, despite using the oxytocin spray twice a day for several months.
The University of California researchers said the improvements were 'in keeping' with those of Viagra.
They concluded: 'These findings support trials directly examining the use of oxytocin to treat problems in this vital aspect of human function, especially in the context of stable, loving relationships.'
Others said that as Viagra does not work in all cases, there is a great medical need for a new drug.
Mike Wyllie, one of the team of scientists that discovered and developed Viagra for pharmaceutical giant Pfizer, said that for some men who have had surgery, the little blue pills can work in as few as 10 per cent of cases.
With sales of Viagra and similar pills reaching almost £2.5billion year worldwide, there are billions to be made.
Dr Wyllie said that a drug based on oxytocin could have 'blockbuster potential'.
However, he warned that drug watchdogs may be cautious about approving a medicine that has emotional as well as physical effects.