Nitric oxide (NO) is a gaseous signaling molecule involved in multiple physiological processes, including the regulation of vascular tone and blood flow. Its role in sexual function, particularly in men, is well-established scientifically. Nitric oxide facilitates the relaxation of smooth muscle in the corpus cavernosum of the penis, enabling increased blood flow and erection. This mechanism is the basis for the action of phosphodiesterase type 5 (PDE5) inhibitors like sildenafil (Viagra), which enhance NO-mediated vasodilation.

Several studies have demonstrated that impaired NO signaling is associated with erectile dysfunction (ED). Interventions that increase NO production or bioavailability—such as supplementation with L-arginine (a precursor of nitric oxide) or L-citrulline—have shown modest benefits in improving erectile function in men with mild to moderate ED. However, evidence for a direct effect of NO or its precursors on libido (sex drive per se, as distinct from erectile capacity) is less robust. Most research focuses on erectile performance rather than sexual desire, and the distinction between these is important.

In summary, there is scientific validation for the use of nitric oxide-related therapies in supporting erectile function, a component of male sexual health. Evidence for a direct impact on sex drive or libido is weaker, but the overall scientific rationale for enhancing sexual function via NO pathways is well-documented for erectile issues.