You’ll also need to fill out a medical questionnaire with answers about your medical history, current medications, and lifestyle habits. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. It might work longer if you have mild to moderate erectile dysfunction. If you have an erection that lasts more than 4 hours, get medical help right away. We also looked at additional services, such as access to digital pharmacies and home delivery options. Generic versions of sildenafil, vardenafil and tadalafil are available.Yes, Viagra is safe for most people to take. But be sure to talk with your doctor before starting this drug. If you have certain medical conditions, such as heart disease, Viagra . “Generic Revatio is considerably less expensive, and it is the same drug as Viagra with the same safety and effectiveness,” says Bradley Anawalt, M.D., an endocrinologist and . With online ED prescriptions, you can easily access FDA-approved medications from the convenience of your smartphone or computer—and the medications can be shipped .