The inhibitors of cyclic guanosine monophosphate (cGMP) phosphodiesterases type 5 (cGMP-PDE5) such as sildenafil citrate (Viagra®) act by increasing the level of cGMP in sexual organs to produce enhanced blood flow and an erectile response of sexual organs. Though sildenafil citrate is a specific inhibitor of cGMP-PDE5, its effects on other body organs produce many side effects including fatalities. Described here is a method of combining cGMP-PDE5 inhibitors with natural sources of nutrients that instantly enhance the levels of endogenous cGMP and thus reduce the therapeutic dose and therefore the side effects of cGMP-PDE5 inhibitors. We have discovered that if sildenafil citrate, as a prototype of cGMP-PDE5, is combined with L-arginine, ginseng, vitamin B6, vitamin B12, and folic acid, all natural and safe ingredients, the dose requirements for sildenafil citrate can be reduced substantially. The specific composition described here assists in the action of sildenafil primarily by increasing the production of cGMP through modulation of nitric oxide pathway (L-arginine→nitric oxide→cGMP) and secondarily by having its own effect on improving blood circulation to sexual organs.