Young men typically experience their peak sexual activity, with the greatest number of different partners, in their 20s. Thus it is during this period that the risk for contracting STIs is highest, and the need to practise safe sex paramount.
There is a slow decline in sexual functioning as men move through their 20s and into their 30s, but this does not become an issue for most men until later. From a peak at about age 18, there is a gradual decrease in the capacity for erection and ejaculation. Testosterone production starts to slow down after the mid-20s, with the result that men may notice that sexual responsiveness is slower.