According to Wikipedia, it was developed to treat hypertension and angina, then the researchers discovered a happy (and very marketable) side effect during tria

According to Wikipedia, it was developed to treat hypertension and angina, then the researchers discovered a happy (and very marketable) side effect during trials. https://en.wikipedia.org/wiki/Sildenafil#History https://en.wikipedia.org/wiki/Sildenafil#History