A real pharmacy will always need to know your prescription. Many online pharmacies may also be unregistered. Popular ED medications found online include: Viagra sildenafil : As the first FDA-approved PDE5 inhibitor for ED, sildenafil is taken 30 minutes to four hours before sexual intercourse to help achieve and maintain an erection. This allows the smooth muscles in the penis to relax and fill with blood. It’s available in 50 mg, mg, and mg tablets. Fact checked by Heather Mercer Print Many of us want the option of purchasing our prescription drugs from online drugstores because the practice seems convenient and money-saving. There are many safe, reliable online services offering ED prescriptions.Cialis is a medication approved by the Food and Drug Administration (FDA) often used to treat erectile dysfunction (ED) and benign prostatic hyperplasia (BPH) in . Medical Consultation Required: Yes Medications Prescribed: Viagra, Cialis, sildenafil, tadalafil Generic offered: Yes Why We Chose It. Yes. The following products are equivalent to Cialis: tadalafil tablet;oral Manufacturer: ACCORD HLTHCARE Approval date: March 26, Strength (s): .