Researchers warn that Viagra can put men's fertility at risk

Viagra actually reduces men's fertility by decreasing the ability of their sperm to fertilize an egg, according to a study conducted by researchers at Queen's University Belfast and published in the journal Fertility and Sterility.

Researchers carried out two different experiments to determine what effect the popular drug might have on sperm cells.

In the first study, human sperm samples were bathed in weak Viagra solutions, intended to approximate the blood concentration acquired from taking a single 100-milligram Viagra pill. They found that while the Viagra-bathed sperm became more active, they also suffered damage to the structure at their heads known as the acrosome. This portion of the cell contains enzymes that help break down the membrane around an egg so that the sperm can penetrate it.

Viagra is a top selling oral medication used in the treatment of erectile dysfunction. Viagra is available in the form of tablets ("blue pills") in three main strength such as 25mg, 50 and 100mg. Viagra is taken orally one hour prior the sexual intercourse and its effect lasts nearly 4 hours. Depending on how well Viagra drug works and how it is tolerated, a health care provider may lower and increase daily dose. The standard daily dose for the most adults is 50 mg once daily.

Maximal daily dose is 100mg. In spite of its high effective and safety profile, Viagra is contraindicated in several conditions and side effects are common as well. These Viagra side effects include: headache, hot flashes, dyspepsia, dizziness, nasal congestion. The majority of side effects are associated with inhibiting PDE5 not only in the corpus cavernosum but in the stomach, nasal mucous lining. According to official Viagra's website the medication does not affect fertility. However, this Pfizer's claim has been properly examined at Queen's University Belfast.

To determine if this cell damage actually affected fertility rates, the researchers compared the fertility of two groups of male mice, one of which had been given Viagra drugs. They found that mice in the Viagra group produced 40 percent fewer fertilized embryos than mice that had not been given any drugs.

The professor David Glenn pointed that the many fertility clinics prescribe Viagra in order to increase sperm counts may actually be harming the fertility of their clients.

"I think it is worrying that some in-vitro fertilization clinics are using Viagra in order to boost fertility results," Glenn said. "Couples that go there for treatment are, by definition, already having problems getting pregnant. Giving male partners something that could make the problem worse is scarcely the right approach."Glenn also expressed concern over the long-term effects that recreational Viagra use might have on people's fertility.

"Viagra has become a widely used recreational drug," Glenn said. "It is mixed with cocaine, for example, and is sold in clubs. Our work leaves open the possibility that there could be a cumulative effect from taking Viagra, however, which could pose serious fertility problems in later life."