Viagra is a kind of oral medication that is meant to be used by men who are suffering from erectile dysfunction (ED). Its generic name is sildenafil citrate and is manufactured by Pfizer.

Viagra comes in little blue diamond-shaped pills with the word Pfizer imprinted on the side.

It is also sold under different names, one of which is Revatio. Though it is perhaps the most popular medication used to treat ED, it has other competitors in the market including Cialis (tadafil) and Levitra (vardenafil).

It was first synthesized by Pfizer chemists in Sandwich, Kent in England. The original purpose of the compound was to treat hypertension, more commonly known as high blood pressure, and angina pectoris, a cardiovascular disease.

However, during the clinical trials, the researchers found out that the compound did not really help alleviate angina symptoms but instead, helped induce penis erections. As such, Pfizer decided to market it as a treatment for ED.

Viagra was approved by the USFDA in 1998 and became the first ever drug to be approved for the treatment of ED. Though it remains a prescription drug, Viagra has been promoted publicly and widely on television and other media.

The dosage would normally be prescribed by the medical practitioner although the recommended amount is about 25 mg to 100 mg once a day.

The pill should be taken anywhere from 4 hours to 30 minutes before sexual intercourse.

Viagra pills are available in various dosages such as - 25 mg, 50 mg, and 100 mg.

However, as with all other medication, it is possible that some side effects may occur, depending on the person. Some of the observed side effects include headaches, facial flushing, and an upset stomach.

Based on reports, however, these occur rarely and when they do, the effects are mild and do not last for more than a few hours.

Other side effects which are less common include bluish or blurred vision, which is temporary, and sensitivity to light. Based on clinical studies, the side effects tend to diminish or disappear over time.