to the best of my knowledge, there is no such thing as
generic Viagra.
Viagra is a cash cow for Phiser, and ten years ago a SINGLE pill was 10 dollars, NOW a single bill is 30 Dollars. Every time the time period lapses for this drug to qualify for generic, they tie it up with paperwork-refile with a slight change to keep the generic out of it. If you are getting something from outside the us, it is likely not Viagra at all.