Contact your medical provider if you experience any side effects during treatment. Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours. Rarely reported side effects include: an erection that will not go away priapism. When taken at the correct time and paired with sexual stimulation, the erection lasts long enough for successful intercourse. This site is intended only for U.(BUSINESS WIRE)–To meet the needs of consumers who are increasingly going online to purchase prescription medications, Pfizer today launched Viagra ® home delivery, a . According to price-comparison site test1.ru, generic Revatio will cost you as little as $ per pill, depending on where you fill your prescription. That’s compared with . If you’re interested in buying Viagra online, five of the best options available are Hims, Roman, Lemonaid, Optum Store, and REX MD. Read on for full details on the process .