No. Viagra is going to do its thing regardless of your choice of underwear. Therefore, you can wear whatever you want and be confident that it’s not affecting your ability to have erections and enjoy sexual activity.
There are plenty of myths surrounding sexual and erectile functioning, and while there’s a grain of truth in some of them, many are simply myths.
Tight underwear, over time, can result in lower sperm counts, but it doesn’t affect your ability to have erections. Therefore, if you experience erection problems, don’t blame your underwear, because the problem lies elsewhere.
Doctors know far more about erection health than ever before. In the years before discovery of Viagra, many doctors thought of erectile dysfunction as primarily a psychological problem, or simply “part of getting old.” But the men who first took the drug that would become Viagra, and who reported that while it didn’t help with their heart problems (angina in particular), it did help them have great erections, helped put medical science on the right path. For most men, erection problems are circulatory problems, and anything you do to improve circulation will ultimately affect erections as well. Tight underwear, while it can cause problems with sperm count, is not to blame for erectile dysfunction.