Sex drugs like Viagra might make men more capable of having sex... but none of these meds provide an invisible protective sheath for your privates.

That may sound obvious, but apparently it's not obvious enough--because a new study finds that men who use sex drugs have triple the risk of coming down with a sexually transmitted disease.

Researchers looked at data on more than 1.4 million men over the age of 40, including some who used penis pills such as Viagra, Cialis, and Levitra, and found that men on the meds were far more likely to have any number of STDs.

The drugs aren't causing the STDs, of course, and the researchers say their study can't pinpoint the exact reason for the increased risk among pill-poppers.

But we can all take a few guesses.

"We are typically unaccustomed to practice safe sex over the age of 50, because the risk of pregnancy is eliminated," Dr. Anupam B. Jena, author of the study in the Annals of Internal Medicine, told Reuters Health.

It's also entirely possible that many men may be so thrilled at the idea of having sex at all that they simply haven't even considered their disease risk.

But the biggest reason of all may be that men who would turn to a dangerous pill to boost their sex lives may be more prone to risky behavior anyway. After all, there are plenty of other risks in those pills--and they can be far worse than STDs.

Sex drugs can lead to breathing problems, headaches, stomach pains and flushing. They can also cause heart attacks and stroke, especially if you're already at risk for those.

These meds can even cause a painful erection that won't go away--and hold the jokes for a moment, because there's nothing funny about the cure. It usually involves a trip to the emergency room... and could involve a scalpel.

Believe me, you'd take herpes over that.

Sex drugs can even make you go blind and deaf--but at least you'll still be able to feel. That'll come in handy when the burning sensation kicks in, letting you know that your drug-fueled sex came with a bonus.