New Male Contraceptive Could Shrink Your ‘Nads with Nanoparticles

  • What’s next? Applying a phaser to your crotch?

There are plenty of contraceptive methods available for women, but men’s options are woefully limited. You can either use condoms, which doesn’t suit those allergic to latex, or get a vasectomy, which stops you from having babies for good.

To remedy the situation, researchers are investigating all kinds of alternatives — like the warm-water testicle bath we covered a few months ago. But now scientists are probing another method that sounds like it’s straight out of science fiction.


A study from July 2021 found that nanocontraception could be worth pursuing as a human contraceptive. The method relies on nanoparticles — tiny pieces of metal that are only a thousandth of the width of a human hair in diameter.

In theory, it could be possible to introduce nanoparticles into the body of a human male. Once inside, doctors could then use a magnet to guide the particles into the testicles.

Once in the gonads, doctors would then carefully heat up the nanoparticles. Sperm viability plunges in high temperatures, so heating up your testicles could essentially neutralize your little swimmers.

Now imagine this banana, but without the condom but full of tiny iron particles.

That’s So Hot. Too Hot!

Nanocontraception isn’t exactly a new idea. It was first tested on animals already back in 2013.

At that time, biologist Fei Sun and his multidisciplinary team was researching nanocontraceptive methods on mice. To test the procedure, they injected gold nanotubes directly into the mice’s testicles.

Yes, we know — having gold injected into your balls doesn’t sound very pleasant. But bear with us.

Once the gold particles were in the mouse testicles, the researchers used infrared radiation to warm them up. As a result, the nanoparticles heated up to temperatures between 98 and 113 degrees Fahrenheit.

But there was an unfortunate side effect to the treatment. The intense infrared radiation caused heat lesions on the mice’s testicles.

Having your balls burned would probably keep you from procreating, but that’s really not what the scientists were going for. So, they returned to the drawing board.

Iron Beats Gold

In 2021, Sun’s team released the results of their new and improved contraceptive methods. This time, instead of using gold tubes, they opted for particles made out of iron oxide.

Also, instead of injecting them straight into the ‘nads, the scientists injected the particles into the mice’s veins elsewhere. They then anesthetized the mice and used a magnet to pull the iron particles to the testicles.

The iron injection and gathering procedure was repeated daily for one to four days, depending on the mouse. Then, the researchers wrapped an electric coil around the mice’s balls and subjected the iron nanotubes to a magnetic field.

This heated up the tubes as effectively as the infrared radiation, but without causing burns. And sure enough, the mice’s fertility plummeted.

The good news about the nanoparticle treatment is that the contraceptive effect is not permanent. After about two months, the mice’s fertility began to rise again, which indicates that they were on their way to normal reproductive health.

Using iron particles instead of gold also has an additional benefit. The gold particles stayed in the testicles permanently, whereas the animals’ livers and spleens eventually removed the iron nanotubes from their bodies.

As a result, Sun’s team suggests that using iron over gold reduces the risk of long-term toxicity.

Small Ball Treatment

However, there are some caveats to the nanoparticle and heat treatment. The first risk factor is excessive heating.

Warming up your balls could be an undeniably effective contraceptive method. However, if you heat the testicles up too much, they can be irreversible damaged.

As a result, even if the nanoparticles exited the body and the testicle temperature returned to normal, sperm production would never recover. In essence, you’d be forever unable to father children.

Speaking to The Conversation, Sun also questioned whether human men would be willing to be put under anesthesia for several hours while doctor wrap electric coils around their balls. And then there’s the fact that the nanoparticle treatment physically shrinks your testicles.

Although the testicles will regain their size with time, would men be comfortable living with shrunken ‘nads? Finally, the procedure’s toxicity on the human body hasn’t been clarified yet.

There’s a lot of work to do before nanocontraception can be used on humans. Meanwhile, in some countries — like China — zoos and pet owners are starting to use the technology to get a better idea of its effectiveness.

Perhaps in the future, once all the kinks have been hammered out, we can rely on nanoparticles to prevent unwanted babies. In the meanwhile, though, a good old condom is men’s best option.

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