Fildena is a medication used to treat erectile dysfunction (ED). It's available as the brand name drug Viagra(r) and as a generic version. It's often used as an oral solution, taken as needed, and it comes in a variety of doses. It can also be injected, but it's not usually as effective. This drug can be taken about 30-60 minutes before sexual stimulation. It should not be taken more than prescribed by a doctor.