Caverta (Generic Viagra) is Ranbaxy's brand of "sildenafil citrate".Viagra is the latest oral drug introduced for the treatment of a condition known as "erectile dysfunction" (ED). Viagra can help many men who have ED, get and keep an erection when they become sexually stimulated.The main chemical of Viagra that is Sildenafil Citrate works on an enzyme working mainly in penis.This enzyme does not allow penis arteries to dilate and therefore Viagra inhibit the effects of this enzyme thus allow arteries to relax and widen so that more amount of blood circulate in the penis and less amount of blood come out of penis causing a good erection of penis.

The name of the drug is derived from 'Corpus cavernosum' a chamber in the male organ which plays a key role erection.
Viagra allows an erection only in response to sexual stimulation and is of no use in women and children. It doesn't cause erection by itself.

Side Effects of Viagra.

Viagra (sildenafil citrate) can cause some side effects. The most common side effects are headache, flushing of the face and upset stomach. Less common side effects that may occur are temporary changes in colour vision (such as trouble telling the difference between blue and green objects or having a blue colour tinge to them), eyes being more sensitive to light or blurred vision. In rare instances, men have reported an erection that can lasts for more than four hours. In that case call a doctor immediately . If not treated right away, permanent damage to your penis could occur.