Background: Sexual Dysfunction and Current Drug Therapies
Sexual dysfunction is a common complaint among both men and women. By some estimates, over 40% of American women suffer from a loss libido, difficulty reaching orgasm, or other sexual troubles. Meanwhile, more than 30% of all men have trouble achieving or keeping an erection, a condition known as erectile dysfunction.
In both men and women, sexual stimulation causes activity in the nervous system which, in turn, causes local release of nitric oxide in the genitals, stimulating a substance called cGMP that increases blood flow causing sexual arousal an erection in men and clitoral enlargement in women. The biochemical steps that lead to orgasm, however, are poorly understood.
Viagra and similar drugs block the breakdown of cGMP in the penis specifically. The net effect is to increase cGMP's effect in the penis, increasing blood flow to the penis during arousal, producing a more lasting and possibly more complete erection than would otherwise occur. To clear up a common misunderstanding, these drugs do not cause instant erections. If a man isn't aroused, he won't be making any extra cGMP and blood won't rush to his genitals.
Viagra was the first breakthrough treatment for erectile dysfunction, but it and similar drugs like Cialis and Levitra have limitations that only increase the appeal of natural alternatives. They can be expensive costing as much as $10 per pill and are often not covered by medical insurance. They should be avoided completely by men taking medicines that contain nitrates such as nitroglycerin because the combination can cause a dangerous drop in blood pressure. They can cause mild to moderate side effects such as headache and visual disturbances. In rare instances, men have reported erections that last many hours, which is painful and can potentially damage the penis. Heart attack, stroke, irregular heartbeats and death have also been reported rarely in men taking Viagra, although it is not possible to determine whether these events were directly related to the drug.
Although the search continues, there are no impressively successful prescription drug treatments for female sexual dysfunction.
The Evidence for Supplements for Sexual Enhancement:
Many supplements have been touted as natural remedies for sexual dysfunction. These products contain a wide array of herbal and other ingredients. As the summary below makes clear, there isn't much sound clinical evidence to support the use of most of these ingredients. This does not necessarily mean that they don't work, just that they are so far unproven. Without well-designed clinical studies, it's hard to know the appropriate doses or potential safety concerns. Be aware that supplements often combine ingredients in a product, making the end results even less predictable unless that specific combination has been tested.
Sexual dysfunction is one matter. Numerous products, often sold on the web, also claim to enlarge the size of the penis. Such claims are completely unfounded. There is no way short of surgery to increase a man's natural penis size. Many of the "penis enlargement" products claim the same ingredients found in products for treating erectile dysfunction. At best, these products will only help with an erection -- a temporary increase in penis size.
It should also be noted that some natural products may actually decrease libido. For example, soy isoflavones and licorice may lower testosterone in men, and the supplement androstenedione may raise estrogen levels in men without raising testosterone; either of these effects could lead to reduced libido in men.