Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Of the half-dozen Viagra-type drugs on the market now, Viagra itself may still have “the greatest efficacy, but also has the highest rate of overall [side] effects.” It’s still a pretty safe drug. Some guy swallowed 65 at a time in hopes he’d go out with a bang, but it didn’t work. The most commonly-observed acute side effects include headache, flushing, stomach upset, runny nose, and vision abnormalities. But now that it’s been around for a decade, some chronic effects may be cropping up—for example, glaucoma, “one of the leading causes of blindness,” caused by degeneration of the optic nerve. Up to nearly ten times the odds of glaucoma among those using Viagra long-term.

But, it’s cancer that has the medical community rethinking the safety of these kinds of drugs. Men with advanced prostate cancer often have to get a radical prostatectomy, a surgery that can leave them both incontinent and impotent, which can reduce their quality of life. Therefore, a treatment concept called “penile rehabilitation” was introduced, where drugs like Viagra are given to counteract the side effects of the surgery. But, there have been studies like this, that found Viagra could decrease natural killer cell activity, and natural killer cells are our first line of immune defense against cancer. Now, this was a study on women for something else, but it did raise concerns about giving Viagra to those battling prostate cancer.

In terms of getting prostate cancer in the first place, men treated with Viagra-type drugs “tended to have less of a chance of being diagnosed with prostate cancer.” Yeah, but that may just be because they’re ejaculating more. “[H]igh[er] ejaculation frequency may be associated with a lower risk of…prostate cancer.” It’s interesting the reason they think why. “Frequent ejaculations may decrease the…concentration [within the prostate gland itself] of xenobiotic compounds [like hormone-disrupting chemicals] and…carcinogens.” Anything we eat can end up in our prostate. Drink a cup of coffee, and you end up with caffeinated semen ten hours later. Smoke a cigarette, and the nicotine ends up in the same place. Or eat fish, and end up with one-seventh the healthy sperm count, perhaps because there’s like three times the concentration of PCBs. But, anyway, you don’t know for sure about Viagra, until you put it to the test.

Nearly 5,000 prostate cancer survivors were followed, and those taking Viagra-type drugs did seem to have a little bump in their risk of the cancer coming back. But subsequent studies failed to find such an association. What moved me to make this video is the “unexpected connection” between Viagra and melanoma skin cancer.

“If treated early, melanoma can be cured by [cutting it out], but due to its proclivity to metastasize, in about 20% of patients, it progresses to an aggressive invasive disease” that can kill in a matter of months. And, part of the way it does this is through a gene mutation in the cancer that induces melanoma cell invasion by downregulating an enzyme called phosphodiesterase 5. Does that word look familiar? That’s what Viagra does. Viagra works because it’s a phosphodiesterase-5 inhibitor. So, Viagra may have the same effect in terms of promoting melanoma growth. You don’t know, though, until you put it to the test.

And, Viagra use was associated with an 84% “increased risk of subsequent melanoma” diagnosis. And, you put all the studies together, and the association remains significant. So, here we have this class of drugs “found in medicine cabinets” across the country, and the FDA does its best trying “to ensure the safety and efficacy of such drugs.” But, you can’t “always anticipate the molecular consequences of inhibiting major cellular pathways.”

There is, however, an alternative explanation. Maybe users of Viagra are just naked more, thus giving their partners the opportunity to notice some suspicious mole or something, as only about one in three melanomas are “discovered by the patients themselves.”

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