Comment by WalterBright

First NIH said it does:

https://www.nih.gov/news-events/nih-research-matters/viagra-...

Then it doesn't:

https://www.nih.gov/news-events/news-releases/nih-dream-stud...

Then it does:

https://www.ox.ac.uk/news/2024-06-07-sildenafil-viagra-impro...

Who knows what to believe.