viagra

Viagra, also known as sildenafil citrate, is marketed by the pharmaceutical giant Pfizer. It is also sold under the name Ravatio and Caverta. Viagra was created to treat erectile dysfunction, or ED. It comes in the form of a blue pill in 25mg, 50mg, and 100mg dosages. And even though it's supposedly available only by means of a doctor's prescription, there are many websites on the internet that sell Viagra.

Viagra was originally released in the early 1990s with the intention of treating a form of cardiovascular illness known as angina pectoris. In other words it was never meant to be used for ED.

However, while Viagra was found to be unsuccessful for its original intention, researchers noticed its ability to induce erections in male study participants. It was then patented in 1996 with the intention of being a treatment erectile dysfunction. By 1998 Viagra had passed all the necessary tests for FDA approval, and hit the market with immediate and huge success.

Erectile dysfunction is an extremely widespread disorder in men, and its causes are many. In fact, one of the top causes of erectile dysfunction is purely psychological. Nearly all men at some point in their lives experience erectile dysfunction or trouble getting maintaining an erection. For these cases, as long as the person is otherwise healthy, Viagra can be tremendously useful. For the relatively few cases of ED which are caused by damage to the nervous system, diabetes, or hypogonadism, Viagra will probably be less useful.

Viagra is classified as a PDE5 inhibitor. PDE5 causes a compound termed cyclic GMP or cGMP to degrade. Since cGMP causes the arterial smooth muscles in the penis to relax, allowing the penis to fill with blood and become erect, inhibiting the action of PDE5 will lead to penile erections so long as the individual is otherwise healthy. Viagra is not the only PDE5 inhibitors available. Others include  Levitra, and Cialis.

Here are the main possible side effects of Viagra: headache, upset stomach, flushing, and sweating. Occasionally, users of Viagra will experience blurred vision. In even rarer cases a person may experience temporary lose of sight in one or both eyes.

Viagra should not be taken in conjunction with drugs designed for angina pectoris, as together they can induce a dangerous crash in blood pressure. And Viagra should definitely not be taken without a doctors recommendation.