When tadalafil (the lowest price generic version of Cialis®) is taken as needed for ED, it can start working within 30-45 minutes, but reaches peak effect in most men 2 hours after it's taken. Like other ED drugs that are taken as needed for ED, it must be taken in advance of when you plan to be sexually active to give it time to start working.
Tadalafil can also be taken at a lower prescribed dose at the same time every day. When taken in this way over time, you may find an increased ability to achieve an erection anytime you experience sexual stimulation. After beginning a daily regimen of tadalafil, you may be able to have successful intercourse in as early as 4 to 5 days.