A fitness TikToker is warning people about an unsettling experience she had after using a massage gun on her neck. In the video, which has racked up 4.6 million views so far, Sophie Dolce explained that she recently woke up with “the worst kink in her neck.” So she turned to her massage gun for some relief, noting that she targeted her neck, the base of her skull, shoulder, and back. On that day, Dolce used the massager frequently—on a high setting, every 30 minutes between 8 a.m. and 5 p.m.—because it “temporarily” helped ease her pain.

“I ended up getting super sore, red, inflamed…all over where I was using it,” Dolce said in the video. She ended up feeling worse and had trouble sleeping that night because she was “in so much pain.” When she woke up in the morning, the pain had persisted and she felt an unusual lump on her neck. A spurt of panicked googling prompted her to see a doctor immediately. “My doctor was like, ‘Don’t you dare ever use a massage gun on your neck,’” she said, adding that she was warned this can mess with the blood flow in the area that leads to the brain. 

“I originally shared [the video] to spread awareness to anyone who may have done or might be planning on doing the same thing,” Dolce, who creates videos to help others find joy in movement, tells SELF. She said the lump might be due to an inflamed lymph node because she used the device so much, but she’s getting some testing done to be sure. 

Lots of people rely on a massage gun to alleviate muscle soreness, tension, and pain—so we asked experts about Dolce’s PSA, and they said she’s right to call attention to it.

Why you shouldn’t use a massage gun directly on your neck

Several people in the comments of Dolce’s post said either they or a loved one had experienced a stroke or seizure after using a massage gun on their neck—and this is, in fact, a risk. As Dolce mentioned in her video, there is a pair of carotid arteries on each side of your neck, which have the very important job of moving oxygen-rich blood from your heart to your brain and the rest of your head.

“You do not want to use percussive therapy—a massage gun—over an artery,” Ryan Krzyzanowicz, DAT, the director of athletic training education at the University at Buffalo in New York, tells SELF. Percussive devices generally deliver “rapid pulses in short bursts of pressure” straight into your tissues, as one paper puts it. So when you’re using one right on your neck, “we get worried about blood flow to the brain. In theory, percussion could temporarily starve the brain from blood flow, causing a mini stroke or stroke-like symptoms.” (This could include sudden confusion or trouble speaking, numbness or weakness on one side of the body, a quick-hitting and severe headache, and trouble walking or seeing, among other things.)