1st April 2004

Researchers from Belfast reveal today that men who take Viagra when they are hoping to start a family could be affecting their fertility.

A group at the Department of Obstetrics and Gynaecology at Queen’s University Belfast have shown that while Viagra enhances sperm motility it also seems to speed up the ‘acrosome reaction’, which normally occurs only when the sperm reaches the egg.

The acrosome reaction enables the sperm to fertilise the egg. It releases digestive enzymes that break down the egg’s protective outer layer, allowing the sperm to penetrate more easily.

Forty-five samples of semen were split, half treated with Viagra and half were used as control, it was seen that up to 79% more sperm were fully ‘reacted’ in the Viagra samples.

If the acrosome enzymes are released too early, as seen in this study when Viagra is present, sperm are rendered infertile. This is backed up by studies on mice showing that in the presence of Viagra significantly fewer eggs are fertilised, and fewer of the resulting embryos develop to blastocyst stage (~5 days).

Dr David Glenn, who presents the work today, commented ‘Nearly half of licensed fertility units in the UK currently use Viagra to assist patient semen production. Our study raises questions about the drug’s use in assisted reproduction.’

Notes for Editors

1Viagra affects sperm function in vitro is presented at The Annual British Fertility Society Meeting 2004 on Thursday 1 April 2004, in Cheltenham, UK

2DRJ Glenn, N McClure and SEM Lewis from School of Medicine, Obs and Gynae, Queen’s University, Belfast, Northern Ireland, UK