Viagra increase the sexual response in those who have the capacity to respond

For Viagra to work, the penis needs healthy nerves and arteries.

So while Viagra may be worth a try if you have a condition such as diabetes, only half the diabetic men tested in trials had improvements in their erections.

If your pelvic nerves or arteries have been damaged, Viagra might not perform miracles for you either – the success rate is only 40 to 50%.

Viagra is available for about one in five people with erectile dysfunction in Britain.

Medical categories include all men treated for prostate cancer, those with kidney failure and those who have had polio. These medical conditions join a list of those previously considered eligible for treatment with Viagra including men who have had radical pelvic surgery or their prostate removed, and people suffering from spinal cord injuries, diabetes and multiple sclerosis.

As a rule of thumb, you have to be fit enough to walk up a flight of 20 stairs without getting breathless to qualify for Viagra.

Pfizer say it shouldn’t be taken with heart drugs that include nitrates.

There are also some potentially serious side effects taking Viagra.

The US Food and Drug Administration reported the most common were headaches, flushes, upset stomachs, stuffy noses, urinary tract infections, changes in vision and diarrhoea. There are alternatives to Viagra that may be superior.

Some allow for what might be thought a normal sex life, as they last longer. Cialis is one of these. But population statistics suggest his predictions have not come to pass. Fatherhood rates among older men, always minuscule, have not risen since Viagra came on the market.

According to the National Center for Health Statistics, they amounted to 0.3 live births per 1,000 men over age 55 from the mid 1990s through 2005 before dropping to 0.2 births per thousand in 2006, then rising to 0.4 in both 2007 and 2008, the latest year for which statistics are available. That puts birthrates of men over age 55 exactly where they were in the early ’80s.

The real effect of Viagra seems to be subtler. A 62-year-old man, who asked that his name not be disclosed, described in an interview how his experience helped change his attitudes about aging.

The man, a widower who has been in a long-term relationship since 2004, said he initially looked to Viagra, as a savior. “This is going to give me back everything,” he said.

But that wasn’t the case. The man said he has ended up using Viagra on and off for the last 10 years. But he no longer believes Viagra is necessary.

“In some ways Viagra is a nice addition, but not so important that I need to have it every time,” he said. “We’ve sort of made an adjustment.”

Therapists and others who counsel people on relationships say that the very existence of pills like Viagra have heaped expectations on an age group that may have more concerns than just whether they can still have sex. (It’s stressful enough at 30. But 70?)

Leonore Tiefer, a clinical psychologist and sex therapist in New York, recalled two patients, a couple in their 70s, both widowed. Their experiment with Viagra had been unsuccessful.

“They were eager for companionship but somehow they both felt they ought to be having sex,” she said. “I said you are supposed to be free of this kind of imperative at this point in your life. Why do you think you ought to be doing this?” The ensuing dialogue, she said, went along the lines of the following: “I thought you wanted to.” “I thought you would have wanted to.” It turned out neither one of them cared.

For more news stories about Viagra please click here.