Once you get an erection, you slip an elastic ring or band around the base of your penis. These let you control when and how long you have an erection. For example, cocaine constricts blood vessels, and sildenafil citrate does the opposite. Online pharmacies don’t always hold up to scrutiny, either. Your penis might feel cold to the touch. The erection usually starts within 10 minutes and lasts between 30 and 60 minutes.Generic medications: Viagra is the branded version of the generic drug sildenafil. Buying generic versions of ED drugs can save people a lot of money. Buying generic versions of . Additionally, medications like Viagra can cause priapism — an erection lasting over 4 hours that can result in permanent damage. If this happens, you’ll need to get medical . Viagra alternatives range from medical options like Cialis and Levitra to natural methods like acupuncture and even therapy. We break them all down here. When you think of erectile.