Its discovery was a complete accident. Originally the drug’s intended use was lowering blood pressure through nitrous oxide mechanism. This causes blood vesse

Its discovery was a complete accident. Originally the drug’s intended use was lowering blood pressure through nitrous oxide mechanism. This causes blood vessels to dilate making them wider and reducing pressure. Fun fact: erections in humans are not caused by blood being pumped into the penis, but rather by a sphincter that inhibits flow of the blood into the penis relaxing, I.e. opening up to allow blood to enter. This sphincter has a high affinity to this nitrous oxide mechanism. A serendipitous side effect it seems… Now, on to the answer to your question… Prior to Sildenafil, the common recommended treatment was high doses of L-Arganine an amino acid which is available over the counter (which is used in Nitrous Oxide production, another was Amyl Nitrite - Yes the 70s Disco drug (and gay sex favorite) is also a vasodilator that breaks down to NO2 in the blood stream once inhaled - of course the action was fleeting, and there was a distinct possibility of fainting due to oxygen depletion. So there were treatments prior to Viagra, but they weren’t necessarily efficacious or as long lasting as Viagra.