I'm told (friend of a friend, ha ha) that the "herbal remedies" available from Chinese herbal shops really do work.
They, like viagra, are just vaso-dilators ... they relax the capillaries, so that the blood stays where it should be (if you know what I mean).
The only difference is that Pfizer, the manufacturers of viagra, managed to find a drug which reacts in a more localised area. In other words, with "herbal remedies", you might also feel a bit "flushed" in the cheeks.
However, the "friend of a friend" in question assures me that, a few hours after taking them, her other half looks like he's grown a barber's pole (her description) and that it just will not go away without some "relief".
And apparently much cheaper than viagra.