Men who have erectile dysfunction issues can use cheap Viagra online to get relief from it. World's most famous medicine for ED. It belongs to a group of drugs known as PDE5 (phosphodiesterase) inhibitors. They relax blood vessels which allow for an increased blood flow to the penis to help achieve and maintain erections. You can also order sildenafil, which is a cheaper version of Viagra, as it is a non-branded version. It contains the same active ingredient as Viagra and is equally as effective.