Arousal that starts in the brain

This is the best documented thing it does. In men whose difficulty had no physical cause, eight of ten developed clear erections with no sexual stimulation present, with firm rigidity averaging 38 minutes against 3 minutes on placebo, and across twenty men seventeen responded and two thirds reported more desire. Desire is the key word: this acts on the wiring that generates wanting, not on the plumbing that delivers blood. That is a different root cause from the one the vessel medicines address, and it is why this family produced a medicine of its own.