How quickly does Viagra work? After taking Viagra, the medication quickly enters your machine and starts offevolved working after approximately an hour, however you may take it somewhere from half-hour to four hours earlier than sexual interest. which means that you’ll want to take it approximately an hour earlier than sexual pastime, however you’ve got a much broader window of time for when you could nonetheless get a benefit. however, as noted above, it solely works in case you’re aroused.