Viagra 50 mg is now available for sale online overnight with no cost delivery in the USA. It is also known as the blue pill in the pharmaceutical market with a prescription. Very essential for those who have been troubled with ED issues for a long while. Viagra can last for up to 4 hours. As the concentration of Viagra in the blood typically peaks 60 minutes after taking the drug, the effects are strongest around this time. Therefore, it is best to take Viagra around 1 hour before any sexual activity.