New Male Contraceptive: A Warm Bath for Your Testicles

  • Sterile and clean, what could be better?

Yesterday, we brought you the news about scientists shipping ocelot balls across the country. Some of you may find animal genitalia inappropriate, though, so we thought we’d balance it out with a story about human testicles.

A German industrial designer has developed a potential new kind of male contraceptive. The COSO male birth control device, which work by giving your nads a warm bath, has won the first prize at the German James Dyson Awards.


So far, there have only been two contraceptive options available to men — condoms and a vasectomy. The former can be uncomfortable, while the latter will in most cases permanently destroy a man’s ability to have kids.

Rebecca Weiss, an industrial design graduate from the University of Munich, thought there must be another option. She was inspired to look for one after the was tragically diagnosed with cancer.

“About a year ago I was diagnosed with precursor cervical cancer due to contraception with the pill. After that, hormonal contraception was no longer an option,” Weiss told the James Dyson Awards.

“When my partner and I were looking for an alternative method, we became aware of the lack of male contraceptives. … So I decided develop a new contraceptive approach for men as my master’s thesis,” she said.

Photo: COSO/Instagram

A Warm, Bubbly Bath

With her mind set, Weiss got to work on the COSO. Now, her prototype is complete and it seems to work.

COSO looks like a small, plastic, testicle-sized bathtub. The user fills the device with enough water to be able to submerge his testicles.

The thing then heats the water to a comfortable temperature to prevent your little danglers from retreating into your body cavity. All the user then has to do is remove his pants, sit down with his balls in the tub, and the turn the device on.

COSO will treat your testicles with ultrasound, which should stop sperm mobility and generation. Two weeks after the treatment, the contraceptive effectiveness should begin.

To maintain the effect, you’ll have to give to give your testicles a bath every two months. If you decide you’d like to sire offspring after all, all you have to do is stop using COSO — the effect should wear off within six months.

Using ultrasounds to knock out your sperm might sound like nonsense, but it’s based on science. A 2012 study found that the ultrasound contraception is safe and effective.

“So far, the procedure has been applied to animals. Therefore, the technical parameters can be hypothetically transferred to humans,” said Weiss.

Emphasis on User Satisfaction

Weiss didn’t rely on just decade-old studies to develop COSO, though. To begin with, she surveyed 422 males to see if there was even a demand for the machine.

It turns out that there was. Weiss chose male volunteers between 25 and 30 years of age who were in steady relationships and invited them to design workshops.

During the workshops, the volunteers got to tell Weiss what they wanted from the ball bath device. Additionally, she asked them to draw their vision of what the thing should look like.

Based on the sketches, Weiss developed the first design concepts. She also worked with experts in urology, andrology, sexual therapy, and psychotherapy to evaluate the device and its functionality.

“After finalizing the form by sketches, ergonomic prototypes were made of paper and cardboard to test the dimensions on different test persons. Subsequently, the prototype was checked to the largest common testicular size at the urologist and the shape was adjusted to the testicular anatomy,” Weiss explained.

It’s good that she put that much effort into it. After all, the bathtub needs to fit men of all shapes and sizes.

More Work Needed

If you got excited, you unfortunately won’t get to dunk your testicles into an ultrasonic bath just yet. Although COSO won the design award, Weiss only has a hypothetical design in her hands.

She said that the current short-term goal of the COSO project include developing a functional prototype to test its technical feasibility. She also wants to create a proper high-fidelity, full-scale prototype.

Weiss emphasized that she still needs to build up a comprehensive base of clinical data before getting any kind of a product on the market.

“In order to launch COSO as a contraceptive, it needs financial support for clinical trials. This requires contacts in research or industrial partners,” she said.

Still, if COSO is successful, it will provide men with an easy-to-use and quick contraceptive method. As an added bonus, they’ll be getting it on with freshly bathed testicles.

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