Ultrasonic repellers are safe but useless

Ultrasonic mosquito repellers are safe for humans and pets, but they don’t actually repel mosquitoes.

The science is pretty clear here: dozens of studies have tested these devices, and none have found evidence that ultrasonic frequencies keep mosquitoes away. Mosquitoes aren’t bothered by the sound—they don’t even hear it the way we do, and some research suggests a few species might actually be attracted to certain frequencies. So if you’re buying one to stop bites, you’re just burning money.

Are they dangerous? Not really. The sound is above human hearing range, so you can’t hear it. Some people report mild annoyance or headaches from cheap units that leak lower frequencies, but no credible evidence shows any real harm to adults, kids, or pets. That said, I wouldn’t put one right next to a baby’s crib for weeks on end, mostly because we don’t have great long-term data.

Bottom line: they’re a gimmick. A fan or a repellent with DEET or picaridin will actually keep you bite-free. Ultrasonic repellers are just noise—literally and figuratively.