In the universe of The Boys, superheroes get their powers from the drug Compound V, which was first created by a Nazi scientist named John Vogelbaum in the 1930s and which has since entered the gene pool due to V/A complacency on numerous occasions. It's only side effect talked about thus far is that it turns your feces blue.
When Compund V is refined and perfected, the effects result in extraordinary superhuman abilities. Abilities such as super strength, flight, durability, and agility, are just some of the powers acquired from perfected V. Some street level versions of the drug can still grant superhuman abilities like with the G-Men and G-wiz, but unrefined, like in the environment, one in ten thousand times it will lead to mediocre superpowers. Other times, Compound V in the gene pool will lead to cancer, heart disease, and brain damage. The version of Compound V The Boys use was personally created by Vogelbaum; this version didn't make The Boys bulletproof or be able to fly, and wasn't as strong as the Compound V use to create The Seven(because the C.I.A. cut Vogelbaum's funding), but this version still made The Boys 50 times stronger than an average human and gave the super durability.
A powder form of Compound V called "Blue", is taken by prostitutes and gives them super durability for a short period of time so that they will not suffer any injuries when having sex with a superhero.