The Bottom Line VigRX Plus is a scientifically-formulated male enhancement supplement that promises a “bigger, harder, longer lasting erections”. When we looked for evidence supporting these bold claims, we found solid research on its ingredients. We are glad to see VigRX Plus contains icariin. Being a moderate PDE5 inhibitor, icariin stimulates blood supply to the penis and, at the same time, relaxes smooth muscle. It works just like the commonly known Viagra but without the side effects of this drug.