"The times where I've been unable to perform have been some of the more emasculating moments of my life," says 24-year-old Matt, referencing the sexual encounters he's had cut short by his uncooperative penis.

Matt isn't alone. Browse the MRA safe spaces of Reddit or the dusty corridors of Yahoo Answers—or, in fact, speak to other men who have found themselves in a similar situation—and you'll see there's a great deal of shame attached to erectile dysfunction. The validity of that shame is one thing, the remedy—for the majority of men, for the past 20 years—is another: Viagra.

For Matt and many others, those little blue pills call help to "replace this feeling of powerlessness with a sense of control."

Viagra was first marketed to the public 20 years ago this month; its brand name usurping the less catchy "sildenafil citrate," the medication's active chemical. Before its introduction, supposed solutions for limp-dick were crude at best and eye-watering at worst. British scientist Dr. Nicholas Terrett—who is one of Viagra's inventors, and named on its original patent—quips over the phone that the methods of old "were no fun at all," consisting of either "introducing a drug into the urethra" or "having a prosthetic device implanted into your penis."

Suddenly, though, here was "a drug that was orally bioavailable—you just popped a pill," adds Terrett. And funnily enough, this method proved much more popular than anything involving urethras: Within the first few weeks of hitting the market, the diamond-shaped tablets had been prescribed to an estimated 40,000 men.

Famously, Viagra was never intended solely as a boner-boosting drug. Originally developed in 1989 as "UK-92480" by Pfizer scientists Peter Dunn and Albert Wood, it was designed to treat high blood pressure and angina, a chest pain caused by reduced blood flow to the heart. By 1991, Dr. Terrett was on board and a British patent for Viagra as a heart medication had been filed.

It's for this reason that many media reports have painted the proposed angina medication's sexual side effects as a stroke of "luck." However, according to Terrett, the idea that the drug might be able to combat erectile dysfunction was a possibility hypothesized before its first medical trial.

The team of Pfizer scientists—based in Sandwich, Kent—discovered that the mechanism that opened blood flow up to the heart muscles "was pretty widespread through the body... and [so] if we could find a drug that would interact with the mechanistic target, we could maybe treat respiratory disease, gastric disease... and erectile dysfunction," says Terrett. Consisting of healthy volunteers in South Wales, the first medical trial for Viagra showed much more promise in treating that last condition that any of the others researchers had considered, as did other early trials.

"Around the same time, other studies were revealing more information about the biochemical pathway involved in the erection process," writes researcher Ian Osterloh in Cosmos magazine. "This helped us understand how the drug might amplify the effects of sexual stimulation in opening up the blood vessels in the penis. With UK-92480's chances of treating angina now slim, we decided to run pilot studies in patients with erectile dysfunction."

These clinical trials saw a "phenomenal response" from the majority of participants, says Terrett, and with that, the drug's future was set: In March 1998, the FDA approved its use in the US for treating erectile dysfunction, and by June of the same year, Newsweek was calling it the "hottest new drug in history almost everywhere in the world."

Since then, Viagra has made Pfizer more than £1 billion [$1.4 billion] a year. Besides its efficacy in a field a lot people care a lot about, the drug has benefitted from a string of savvy marketing campaigns. Dorothy Wetzel—who started the consumer marketing department at Pfizer—oversaw the first round of advertisements, which included a print ad featuring a photo of an older couple and the tagline "Let the dance begin," as well as a TV spot featuring former US presidential candidate, Bob Dole.

Wetzel told me that the aim was "always a balancing act between wanting to be a responsible healthcare marketer and representing the inherent truths of human sexuality." One of these truths, she contends, is that "the ability to perform sexually is key to a man's sense of self"—and clearly, judging from Matt's comments and the transcribed fretting you'll find online, she was spot on.

For Wetzel, the reason Viagra has become so iconic is because "pills and sex have always had a prominent role in our culture." In the same way that "the birth control pill stood for female freedom," Viagra allowed for a "kind of Peter Pan fantasy," where men could be "forever their essential vital selves."

In recent years, however, there's been a growing number of younger men taking Viagra—or non-Pfizer alternatives, such as Cialis and Levitra—often recreationally. This started as a post-rave antidote for "pilly willy" because stimulants—as you may know—can adversely affect a boner's structural integrity. While no specific studies have been carried out, it's thought that this combination of drugs could cause certain health issues. Still, that doesn't stop people like Matt from using Viagra alongside "stimulants, such as MDMA or speed, but also with alcohol if I think I might have trouble [getting it up]."

As the Spectator reported in early March, Viagra is now being specifically marketed to young men, framed as a "lifestyle" drug rather than a medical one.

I spoke to Meika Loe, author of The Rise of Viagra, about this trend. She sees it as worrying, indebted to our "McDonaldlized world" and a "porn culture" that urges us to be "robotic, sexualized creatures... with perfect 3D erections." While writing her book, Loe spoke to many young men who she saw as being "part of the pharmaceutical generation—they have learned to solve problems with pills." Rather than relying on a quick chemical fix, she would like to see people being "more vulnerable with each other, not less," and treating "the whole body [and the] relationship" rather than just popping a pill.

Terrett is equally worried about the "salacious angle" many media outlets approach Viagra from, and emphasizes that it is a drug intended for medical, not lifestyle, purposes. With this in mind, the real success for Terrett has been seeing the effect Viagra has had on men's health in general—besides opening up the blood vessels within millions of penises, it has also sparked vital conversations about male sexual health.

Another benefit, he says, which has gone widely underreported, is that increased discussion around erectile dysfunction has led to "a discovery that a lot of people had impotence as a consequence of cardiovascular disease that limited blood flow and impaired the mechanism that caused erections." So, in getting a diagnosis, this discussion has directly "extended their lives."

In 2013, Viagra's UK patent expired, allowing rival companies to offer alternatives and prompting Pfizer to release a little white pill at a fraction of the cost of its little blue pill. Pfizer's US patent extends until 2020, but in late 2017, the company started selling its cheaper alternative in America, too.

This week, the UK became the first country where consumers can buy Viagra over the counter without a prescription—an effort to combat the online trade of questionable counterfeit pills, which can be dangerous and has been found to contain everything from blue printer ink to brick dust.

One-fifth of British men are thought to have erection problems, with NHS sildenafil prescriptions tripling to nearly 3 million from 2015 to 2016. While customers will still have to fill out an online questionnaire or answer some questions at a pharmacy before the sale of these new Viagra Connect pills can be completed, Pfizer says they will offer these men "a new and convenient route of access to treat the symptoms of erectile dysfunction."

Whether for medical or recreational use, the demand for Viagra has never been higher. And now, 20 years to the week since the drug was green-lit for FDA use, with the introduction of these new non-prescription pills, they're also more available than ever. How that will affect the next 20 years of sex and male health is anyone's guess.