The concomitant use of erythromycin or strong CYP3A4 inhibitors e. Unless I knew for sure that I would be able to get the drugs and enough to make it worth the cost of the trip. Make sure to get an estimate of when you can expect your prescription in the mail. Maximum observed plasma concentrations are reached within 30 to minutes median 60 minutes of oral dosing in the fasted state. Key facts It usually takes 30 to 60 minutes for sildenafil to work for erectile dysfunction. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Patients are advised not to exceed a maximum dosing frequency of once daily.Generic Viagra (sildenafil) is available as a , , , and milligram (mg) pill and in liquid form. It’s meant to be taken as needed — about an hour before sex — but . To buy or its alternatives in, we recommend to contact your. nearest pharmacy. Call the pharmacy using the number on the. map, to find out if is in stock. Remember to ask the . We would like to show you a description here but the site won’t allow more.