Are you talking about difficulty retracting his foreskin? If so, that is known as phimosis, and Viagra sounds like a very bad idea. Here's some basic info, including treatments: https://www.webmd.com/men/phimosis-paraphimosis Note that Viagra is NOT on that list. If you're asking about something else, please let us know and we'll try to help.
Yes it might help many doctors has prescribed for these some are getting relief some are not getting the relief