Herbal supplements such as ginkgo biloba, saw palmetto, and yohimbe have been touted as sexual enhancers, and some men have been tempted to try them to treat erectile dysfunction. Bennett warns, however, that none has been approved by the FDA or even shown by any reliable studies to prevent, treat, or improve erectile dysfunction. Moreover, supplements are unregulated and can have many side effects or interfere with prescribed medications you’re already taking. Don’t jeopardize your health by taking a supplement to treat erectile dysfunction without first talking with your doctor.
Induction of erection occurs after stimulation of the cavernous and pelvic nerve plexus. Conversely, stimulation of the sympathetic trunk leads to detumescence. The reflex erectile response requires that the sacral reflex arc remain intact. Tactile and sensory signals are received by the somatic sensory pathways and integrate with parasympathetic nuclei within the sacral spinal cord (S2-4) leading to induction of erection via cholinergic signaling. These reflexogenic erections remain intact with upper motor neuron injuries. Psychogenic erections do not require that the sacral reflex arc remain intact. In a cat models, spinal cord removal below L4/L5 led to absence of a reflexogenic erection but stimulation of the medial preoptic area (MPOA) or placement near a female cat in heat led to erection (5,6). Psychogenic erections occur via induction of central pathways traveling from the brain through the sympathetic chain. Non-penile sensory pathways induced by sight, sound, touch and smell travel through the MPOA to the erection centers within the cord T11-L2, and S2-S4 to induce erections (7). When a sacral lower motor neuron injury is present in men, below T12 these types of erections are more likely to occur (8). Spinal cord lesions above T9 are not associated with psychogenic erections (9). Rigidity of erections is less with psychogenic erections because the thoracolumbar sympathetic outflow may contain a decreased concentration of neurons compared to the parasympathetic outflow from the sacral spinal cord.

Sildenafil has been previously suggested as a treatment option for ED in men with epilepsy (77,78). However, Matos et al. warned that PDE5i are potentially pro-convulsant and should be used with great caution in men with epilepsy (79). Animal studies in rat and mice overwhelmingly suggest PDE5i can reduce seizure threshold. In human trials, seizures were rare but reported. PDE5i exerted their proconvulsive effect by lower seizure threshold possibly by worsening sleep or obstructive sleep apnea, causing cardiovascular changes, or leading to EEG changes specifically with tadalafil use.


ED usually has a multifactorial etiology. Organic, physiologic, endocrine, and psychogenic factors are involved in the ability to obtain and maintain erections. In general, ED is divided into 2 broad categories, organic and psychogenic. Although most ED was once attributed to psychological factors, pure psychogenic ED is in fact uncommon; however, many men with organic etiologies may also have an associated psychogenic component.
The most common treatment for erectile dysfunction is drugs known as phosphodiesterase-5 (PDE-5) inhibitors. These include tadalafil (Cialis), vardenafil (Levitra), and sildenafil citrate (Viagra). These are effective for about 75% of men with erectile dysfunction. They are tablets that are taken around an hour before sex, and last between 4 and 36 hours. Sexual stimulation is required before an erection will occur. The PDE-5 inhibitors cause dilation of blood vessels in the penis to allow erection to occur, and help it to stay rigid. Men using nitrate medication (e.g. GTN spray or sublingual tablets for angina) should not use PDE-5 inhibitors.
In addition, when research has shown a nutrient such as zinc or niacin to improve sexual function, it's usually in people who are deficient in it. So, before you stock up on over-the-counter nutritional supplements for ED, speak with your doctor. He can test you for deficiencies and steer you toward the most effective and safest way to treat your erectile dysfunction. 
Begot, I., Peixoto, T. C. A., Gonzaga, L. R. A., Bolzan, D. W., Papa, V., Carvalho, A. C. C., ... & Guizilini, S. (2015, March 1). A Home-Based Walking Program Improves Erectile Dysfunction in Men With an Acute Myocardial Infarction. The American Journal of Cardiology, 115(5), 5741-575. Retrieved from http://www.ajconline.org/article/S0002-9149(14)02270-X/abstract
For best results, men with ED take these pills about an hour or two before having sex. The drugs require normal nerve function to the penis. PDE5 inhibitors improve on normal erectile responses helping blood flow into the penis. Use these drugs as directed. About 7 out of 10 men do well and have better erections. Response rates are lower for Diabetics and cancer patients.
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