The interesting quality of the double entendre is its ability to say two different things with the same set of words. When it comes to the literal meaning, the now accepted international measure of satisfaction in erections is measured by a set of questions. All researchers now standardize their research by using the same questions. Of necessity, they deal with the practicality of hardness and whether penetration is easily made. This involves not just whether the erection is hard, but also long enough to remain comfortably within the vagina during the thrusting. But there is a secondary safety issue and this leads to the alternative meaning. All the drugs used to treat erectile dysfunction have been and continue to be tested extensively. Somehow, these drugs seems to have touched off major scientific curiosity with new clinical trials continuing in 2009, more than ten years after the little blue pills first appeared on the market. Yet there is one very significant omission from all this research. For all the different hypotheses tested by each new clinical trial, not one trial has ever followed up on the participants for more than twelve weeks after the end of the trial. No trial has ever studied what happens to men if they take these drugs over long periods of time.

In one sense, we might conclude there is no cause for alarm. The FDA runs what’s called the Postmarketing Reporting program. Doctors and hospitals have a specific legal duty to report all serious side effects caused by drugs after their release into the open market. Thus, the FDA keeps it finger on the pulse of each new drug as it is taken up by increasing numbers of people in the real world. Some will use it sensibly. Others will abuse it. But over time, a pattern of experience will emerge. It may confirm the findings of the initial research on safety that encouraged the FDA to grant a license. Or it may reveal completely unexpected long-term problems that would never appear in the classic clinical trials which do not often last more than one year. As and when this evidence emerges, the FDA will either require a change in the labeling to warn people of the new problems or, in the more serious cases, instruct the manufacturer to withdraw the drug.

This October has seen the release of a new piece of meta-research which consolidates the results of 49 published trials. This reanalysis of the data from multiple studies allows broader patterns to be detected. In this case, the Canadian team confirm the risk of side effects from the use of viagra increases if men take a higher dosage over time. But, because none of the studies has more than a twelve week follow-up, there is no data on whether the level of risk changes if men continue to take the drug. It’s possible that men build up tolerance and the risk of side effects reduces. No-one knows for sure. The obvious explanation for the lack of multiple reports of side effects is that men accept them as part of the price to be paid for restoring sexual activity. So, let’s take the practical view that viagra remains not only effective but also safe for use both in the short- and long-term.