The wife and I have been taking it for about four months now. It works for both of us but differently. She takes it a few hours before she wants to be "ready". She has about 30 minutes of mild flushing right after the shot. That's how long it takes for her for it to settle out in her system. At that point, she describes it as her clit is "talking to her" and has a very heightened sensitivity. She can't tell if that sparks her brain about sex or the other way around. It lasts a solid two days, sometimes three.
For me, I have moderate flushing for an hour or more. Not uncomfortable but very noticeable. As for erections, they come on randomly starting about six hours later. Unlike cialis or viagra, no stimulation is needed to start them. It just randomly happens. Sounds funny and it is to an extent....just describing what happens to me for the benefit of others. It lasts for two to three days for me as well.
We can't really say that it does anything for us when we are "in the act" but we know others that say it does. So, for us, it definitely starts the engines. Hope that helps.