Cialis helps to temporarily provide men with the ability to get and keep an erection by increasing blood flow to the penis. A man's erection depends on the body delivering - and trapping - the blood in the penis long enough to provide the stimulation and satisfaction for sexual activity. Cialis, in clinical trials, has proven to do this for men who suffer from mild to moderate ED.

The male organ contains two chambers - the corpora cavernosa - which runs the length of the organ. These chambers are filled with a spongy tissue containing smooth muscles, fibrous tissues, some spaces, veins and arteries. The urethra, which is the channel for both urine and ejaculation, runs along the underside of the chambers.

An erection begins with either mental or physical stimulation, or both. Impulses sent from the brain and the local nerves cause the this vein filled chamber to relax which allows an increased blood flow to the area. Obviously, this increase in blood expands the male organ and then the blood is trapped, which is what sustains the erection. The erection is not reversed until the organ contracts to stop the inflow of blood and opens the outflow channels, which then releases the blood.

Cialis works through its ability to help trap the blood flow through the inhibition of a substance called PDE5, which in turn stimulates the creation of a second substance cyclic GMP - cGMP - which is responsible for the relaxation of the muscles in this area causing an increase in the blood flow.

Primary U.S. clinical studies show "meaningful and statistically significant improvement" in the sexual functions of men after using a 20 mg dose of Cialis. These results held steady even with extended use. The efficacy and safety trials involved 402 men whose ages ranged from 27 to 87 years of age. Included in this group of ethnically diverse men were those who suffered in addition to impotence, diabetes, high blood pressure and other cardiovascular diseases. The majority of these men had experienced erectile dysfunction for a minimum of one year.Clinical trials conducted outside the United States revealed the same results. In these studies, the ages of the men ranged from 21 to 82 years, included men whose erectile difficulties stemmed from a variety of reasons, including organic and psychological.The minimum length of time a man had experience erectile dysfunction was one year.

The advantage of Cialis is the ability of the medication to linger in the man's system for up to 36 hours. This allows him and his partner to choose the proper time. The three major erectile dysfunction drugs on the market all work in a similar way. As with any medication, though, each person experiences different results with different drugs. Many men have switched to Cialis because Viagra or Levitra did not work well enough for them. Some men received good results with Viagra but switched to Cialis because of the larger window of opportunity - the advantage of having the ability to make love in a time frame as long as 36 hours.