Other conditions that may disqualify you from an ED prescription include a history of stroke, kidney or liver disease, cancer, diabetes, or a bleeding disorder. These include a heart attack, stroke or a serious heart rhythm disorder in the past six months. When taken at the correct time and paired with sexual stimulation, the erection lasts long enough for successful intercourse. Insurance can help you save even more on consultations and medications. Online ED consultations offer privacy, convenience, and affordability while allowing you to quickly get the medications you need—the same day, with some services. Those with pre-existing conditions should always consult a healthcare provider before taking new medications or supplements. However, some states require a live video consultation.Viagra takes around 30 minutes to become effective and lasts about 4 hours. Cialis lasts much longer — up to 36 hours in some cases. Stendra can start doing its thing in as little . Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription . 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 .