The neurologic pathways required for erection originate in the cerebral cortex where visual, auditory, and psychic stimuli are processed, and in the pudenal nerve, an afferent nerve that transmits tactile sensations from the genitals to the sacral segments of the spinal cord and cortex. Efferent signals from the spinal cord pass along the pelvic parasympathetic nerves and dilate the corporal vessels. The specific neurotransmitters have not been fully defined; acetylcholine, and perhaps vasoactive intestinal peptide, appears to be important. There are many causes of neurogenic impotence. Anything that disrupts neural pathways or blocks neurochemical transmission will have an adverse effect on erection. Psychologic factors probably interfere with erection by inhibiting corticosacral efferent pathways.
The 4 ED medicines we prescribe – Generic sildenafil 20 mg, Viagra (also sildenafil), Cialis (Tadalafil), or Levitra (Vardenafil) - are generally safe but shouldn’t be used as recreational drugs. They’re meant to treat a medical condition and can cause serious side effects including but not limited to an erection lasting more than four hours, sudden loss of vision in one or both eyes, and sudden decrease or loss of hearing.