The world of wellness fads is a cyclical place. Everything comes back into fashion when a new generation of influencers decides to switch it up. Pretty much every current hype was popular in decades past, from extreme juicing to genital sunning and everything in between.

Gua sha is the ancient practice of scraping the skin to form mild bruises – called petechiae – which are thought to do a variety of helpful things for your body. The practice has been around in China for centuries and has spread through the wonders of social media to all corners of the globe.

Gua sha is performed by scraping a smooth stone, coin or similar instrument across lubricated skin in a single direction. Mild bruising might start to appear as a result. Practitioners claim that the resulting petechiae are evidence of “toxins”, and that as they disappear they take these toxins with them. This is said to heal skin, improve blood flow, and even strengthen your immune system according to various people online.

From a scientific perspective, this makes very little sense. The mechanism of action here is similar to a massage, but with a bit more force. Dr Brad McKay, a GP and science communicator, notes that “gua sha provides the same health benefits as a violent massage”. While the practice does certainly increase blood flow to a specific area of your body – that’s what happens when you get a bruise, after all – there’s no evidence that this has any benefit. McKay notes: “A punch to the nose also increases blood flow.”

There’s also no evidence that the petechiae have anything to do with “toxins”. Indeed, they are simply the body’s reaction to any heavy pressure, and can happen when you scrape your skin on virtually any surface. The small dots and bruises will appear regardless of the “toxins” in your body, and should always go away on their own.

As far as evidence goes, there’s very little research into gua sha. One recent review looking at gua sha for perimenopausal syndrome found that most of the trials on the topic were of fairly low methodological quality and unlikely to be useful as evidence. A very small 2019 randomised trial found benefits for gua sha on lower back pain, but it was also not especially convincing.

Part of the problem here is the same issue that acupuncture faces – it’s impossible to test against a convincing placebo because you can’t really blind people to whether they are receiving gua sha or not. Most of the purported benefits – such as alleviating pain or stiffness – are self-reported, which means it’s very difficult to run a good trial on gua sha without polluting your results. When researchers measure hard outcomes that are less likely to be biased by self-reporting, such as hormone levels, there are far fewer benefits to be seen for the practice and only from the lowest-quality research.

Gua sha is one of those practices that I’m sure we’ll keep seeing around. It’s relatively harmless, easy to do, and plays well on YouTube and Instagram. It’s quite easy to see why people want to keep making short videos showing lubricated skin being slowly rubbed by a smooth stone, and why that sort of visual tends to attract a lot of views online.

Realistically, however, I think that gua sha is largely a waste of time. It likely has almost identical benefits to a therapeutic massage, but with the negative of a bit of extra pain, if you overdo it. It’s a bit like the chiropractic v massage question – of the two therapies, both have very similar benefits but one comes with additional downsides that make it worse.

Personally, I’m not going to buy a smooth stone and vigorously rub myself with it. There are better ways to relax than intentionally bruising yourself with blunt objects. As McKay put it, “some people report less pain after undergoing gua sha, but this may simply reflect the compensatory relief felt when the wholloping session is finally over”.

• Dr Gideon Meyerowitz-Katz is an epidemiologist and science communicator and a senior research fellow at the University of Wollongong

• Antiviral is a fortnightly column that interrogates the evidence behind the health headlines and factchecks popular wellness claims