There are no easy treatment options for people with chronic pain. Opioid painkillers like Vicodin and OxyContin can help, but they’re highly addictive and come with a significant risk of overdose. The current epidemic of opioid overdoses (from both prescription drugs and heroin) in the U.S. may be the country’s worst drug crisis ever, killing more than 52,000 people in 2015 alone. Yet some scientific reviews have found that opioids may not even be that effective in the long term.

There are ways to combat chronic pain without pills, though, and a Boston-area technology company called NeuroMetrix is trying to bring drug-free pain relief to the masses, no prescription required. Its Quell electrical stimulation band is designed to reduce chronic pain in regular users, reducing medication use in the process.

The Quell device, which is about the size of a thin wallet, is designed to be strapped to your upper calf—the back of your calf has plenty of nerves for the device to work on—with a stretchy fabric band, much like the workout armbands that hold your smartphone or MP3 player while you run. When you turn the device on, it delivers low-level electrical stimulation to your leg for 60 minutes, then turns off for 60 minutes, then begins the cycle again for however long you wear the band.

One theory scientists use to explain pain perception, called gate control theory [PDF], hypothesizes that nerve fibers can only carry so much information to the brain, and activating the types of nerve fibers that respond to pressure and vibration rather than acute pain can inhibit the transmission of pain signals, effectively “closing the gate” between your brain and those nerves so pain messages can’t pass. According to this idea, the electrical stimulation provided by devices like Quell can block nerves from transmitting pain signals to the brain. (The same idea has been used to explain acupuncture’s pain-relieving properties.)

Opioid medications mimic the effects of the brain’s natural opioid peptides, like endorphins. (The word endorphin actually means “the morphine within.”) While at-home electrical stimulation devices called Transcutaneous Electrical Nerve Stimulation units (or TENS machines) already exist, they work much like opioid drugs, by stimulating endorphin production. Quell works slightly differently—by activating the production of another type of naturally produced opioid peptide called enkephalins.

“Enkephalins are not endorphins, but they act in a similar way,” according to NeuroMetrix founder Shai Gozani, who has a Ph.D in neurobiology as well as a medical degree. When you take opioids for a long period of time, your tolerance for endorphins and the opioid drugs that mimic them can increase. “There are no drugs that mimic enkephalins,” Gozani says, which is helpful both from a drug-tolerance perspective and because if you’re already taking painkillers, Quell provides a different kind of relief on top of what you’re already feeling from the medication. Even if Quell doesn’t make your pain go away entirely, it can work in conjunction with your meds so that you don’t need quite as many prescription painkillers to get through the day.

black Quell device sticking out of the top of the black and blue Quell sports band against a white background
NeuroMetrix

While Quell only attaches to your leg, the influx of enkephalins provides pain relief throughout the body. The company recommends it for joint pain, lower back pain, leg and foot pain, and fibromyalgia. I suffer from chronic back pain, but it’s not concentrated in my lower back, so I was dubious as to whether the device would work for me. In the interest of scientific inquiry, I tested Quell on myself for Mental Floss.

The device turned out to be incredibly simple to set up. You just need to slip the unit into the band and snap the electrodes—which come attached to a long paper strip with four squares of conductive gel—onto the inside. You wrap the electrode strip around your calf using the band, then open up the mobile app. Through the app, you can calibrate the level of the vibrations, rate your pain for that day, and start or stop therapy sessions. (You can control Quell using the button on the device itself rather than the app, but it’s much easier on your phone.)

When you turn it on, Quell delivers electrical stimulation in hour-long sessions, but NeuroMetrix recommends that you do several sessions a day to get the full effect. I tested it out for several months, typically wearing it just before bed and while I slept.

Though the words “electrical stimulation” may make you think of shocks, Quell feels more like a little vibration. Ideally, the sensation should be just short of noticeable—when I sat very quietly, I could sometimes identify the tingle of the electric current, but barely, and when I was up and moving, I couldn’t feel it at all. This is both a strength and a weakness of the product, though. On the one hand, you can go on with your normal life without feeling like you’re being zapped. On the other hand, more than once, I tried to take off the band without realizing that it was in the middle of a treatment cycle and gave my fingers an unpleasant shock (not exactly painful, but not enjoyable either). Occasionally while asleep, I accidentally dislodged the band, cutting short my treatment. And I found that in my tossing and turning at night, I managed to stretch out the fabric band considerably, making dislodging it much more likely.

Quell doesn’t make pain disappear completely. I still have back pain daily, even while wearing the device. It doesn’t work for my knee pain, either. But while the device doesn't eliminate my back pain completely, it does make the pain more manageable. I found that it relaxed my muscles, relieving some of the tension that builds up around the spot where I feel the most pain. After I had technically tried Quell for long enough to review it, I continued to use it nightly. I even shelled out $82 for a three-month supply of new electrodes.

two white electrode strips with blue conductive gel
NeuroMetrix

There’s a good amount of science to back of NeuroMetrix’s claims about Quell, which is FDA-approved as an over-the-counter pain-relieving device. In a a peer-reviewed study in the Journal of Pain Research, more than 80 percent of participants felt an improvement in their pain after two months of use. Around 67 percent were able to reduce their medication usage.

Chronic pain is far from a rare problem, and better options for pain relief that don’t involve pills could make a significant difference. The CDC says that as many as one in four patients taking opioid painkillers long-term becomes addicted. And there are plenty of people who need pain relief. According to the National Institutes of Health, more than 11 percent of the U.S. population (25.3 million adults) suffers from daily chronic pain, meaning pain that has lasted more than three months or, in the case of an injury, when it lasts beyond when the tissue itself has healed. One study estimates that 28 million people in the UK suffer from some kind of chronic pain, often related to arthritis, rheumatism, or back and neck problems.

Most TENS units already on the market aren’t exactly user-friendly compared to Quell. The type of pain relief they provide is localized, so you have to figure out where to place the electrodes for your specific type of pain and deal with interfaces and settings that might as well require a nursing degree to comprehend. And you can’t use them while you sleep, according to the FDA, even though for many people, chronic pain interferes with their ability to snooze.

Quell uses higher-frequency stimulation for longer periods of time than other devices, which is what produces the enkephalin effect. “You’re basically blocking the effect of the pain signals as they come into the spinal cord, decreasing the number of pain signals that come into the brain,” Gozani says. Since not as many pain signals make their way to the brain, you perceive less pain overall. It takes 20 to 40 minutes of high-frequency stimulation (80 to 100 pulses per second, in this case) for the body to begin producing enkephalins, but when you wear the band for several hours per day, it produces more widespread, longer-lasting pain relief than if you used a TENS unit to give yourself a 30-minute rush of endorphins.

It’s also just easy to use. While the $250 Quell starter kit is more expensive than what you’d pay for some TENS units (they range from $30 to $500), the simplicity of the design alone is worth the price. It only takes a second to put on and control, and you can wear it whenever and wherever you want. You can’t exactly sit around in your cubicle or go for a run while hooked up to a bunch of different electrodes, but it’s easy enough to wear a Quell band under pants while walking around. It’s also much more powerful: NeuroMetrix estimates that Quell is five times more powerful than the average TENS device, and unlike the others, it’s approved to use when you sleep. (The device monitors your movements and reduces power to 80 percent when it senses you’re asleep.)

Quell may not work for everyone, and it may not eliminate your pain completely. But even a little relief can be worth it if you’re in constant pain.