Viagra pode causar danos ao espermatozóide.

Estudos britânicos mostram que os pacientes em uso de sildenafil (Viagra), podem ter a sua fertilidade comprometida, uma vez que o uso dessa medicação pode comprometer o potencial do espermatozóide para penetrar o óvulo.
Mas fica a dúvida se esse efeito colateral não estaria sendo produzido pela associação do sildenafil a tóxicos como cocaína, cada vez mais visto nos usuários de drogas nos clubes britânicos.
Porém não foi observado nos estudos com camundongos, qualquer efeito na genética dos filhotes que nasceram daqueles animais, que conseguiram fecundar e que tinham tido o sêmen em contato com o sildenafil em ambiente laboratorial.
Leia o artigo na íntegra, publicado no Daily Mail:

"Viagra could harm sperm and reduce fertility, say researchers"

By DAVID DERBYSHIRE
Men who take Viagra could put their fertility at risk, experts warned yesterday.
Researchers say the drug could harm sperm and reduce its ability to fertilise an egg.
They claim fertility clinics prescribing Viagra to men could be reducing their chances of fathering a baby.
Gynaecologist Dr David Glenn said: "It is worrying that some IVF clinics are using Viagra in order to boost fertility results.
"Couples who go there for treatment are, by definition, already having problems getting pregnant. Viagra may simply be making these worse.
"Giving male partners something that could make the problem worse is scarcely the right approach."
His team bathed human sperm in a Viagra solution to give the same exposure as that seen in the blood of a man after taking a pill.
They found Viagra made sperm more active than if it was not exposed to the drug.
But Viagra also damaged the cap-like structure - or acrosome - that contains the chemicals which allow the sperm to break into an egg.
In tests on mice, sperm exposed to Viagra produced 40 per cent fewer embryos.
Since Viagra was launched in 1998, it has been prescribed to 20million men.
Many are middle aged or elderly and unlikely to be concerned about the drug's impact on their ability to have children.
But Dr Glenn, who raised concerns about the impotence drug in 2004, said younger men using it recreationally could have fertility problems later.
Around forty per cent of IVF clinics have used the drug in the last few years. However, some doctors have stopped recommending it because of its reported links with infertility.
"Couples going to clinics already have fertility problem," he added. "Viagra may simply be making these worse."
The studies were carried out in 2004 and published last year in the journal Fertility and Sterility.