Most male enhancement supplements (Vigrx, Extenze, Enzyte, Spartan Blend, Expanzite, etc.) contain herbs that have been shown to have strong effects on libido and circulation. But, as far as increasing the size of your penis is concerned, the herbs in male enhancement pills do not actually increase size, they do two other very important things: They can increase blood flow to the penis, and can help tone the pelvic floor muscles. More blood flow can lead to larger, harder erections, and toned pelvic floor muscles can make a penis stand more erect. So, they appear to increase size, but in actuality they just help you achieve your full potential.
Talk to your doctor before you take anything, in case of drug-interactions, side effects, or allergic reactions, etc.