Low-intensity shockwave therapy (LIST) is one of the first new treatments for erectile dysfunction since Viagra was approved by the FDA in 1998. It works by nudging the body to produce new blood vessels, which may prove especially helpful to men whose erectile disorder is related to poor blood flow to the penis. LIST is relatively painless and non-invasive, and no major side effects have been noted so far. Men who participated in scientific studies observed improvements in their symptoms within one to three months. But the treatment is still experimental, and more research is needed.