It kind of goes without saying, but TikTok’s viral beauty trends are a mixed bag. Videos can range from helpful hacks and product reviews, to harmless tricks, to genuinely harmful advice that risks causing permanent damage (previously on TikTok: dry scooping pre-workout powder, teens removing their own IUDs, and of course the Gorilla Glue saga). According to beauty experts, the video app’s recent plasma pen trend falls into the latter camp, especially when the treatment is carried out at home. 

If you’re wondering what a plasma pen even is, here’s a brief explainer: the handheld devices are similar in size to an electric toothbrush, with a long metal tip that looks like a needle. However, the pen doesn’t actually touch the skin — the process itself is billed as a non-invasive procedure — but discharges an arc of plasma, which singes a small circle of tissue.

It’s worth noting that the kind of plasma used in this treatment has nothing to do with PRP (or platelet-rich plasma), the component of your blood with the same name that’s used in the infamous “vampire facial”. Instead, the term refers to “the fourth state of matter”, which occurs when a gas is super-heated.

If you’re on TikTok, you’ve probably seen the effects of a plasma pen at some point. At first, it leaves a field of tiny marks on the skin (trypophobes, don’t visit #plasmapen), which can swell, and visibly scabs as it heals over the course of a week or two. The aim? To leave the skin firmer and tighter by inducing trauma that stimulates collagen production, similar to microneedling.

Unlike microneedling, however, the plasma pen chars the skin, which can have undesirable long-term effects. “When you apply heat to tissue, you can tighten the tissue, but you’re denaturing its proteins,” Dr. Lara Devgan, a certified plastic surgeon in New York City, tells Allure. Devgan compares the process of “basically cook(ing) a little dot of tissue” to cooking a raw steak.

“You’re denaturing the proteins of the steak, so you’re fundamentally changing it. The cooked steak doesn’t look anything like the raw steak and it doesn’t move the same way. It has a leathery quality; it doesn’t have the same suppleness.” The same goes for your face, she adds. “If that’s your face, you want the smoothness, suppleness and movement of ‘raw’ or ‘uncooked’ tissue. And so that’s the reason why applying heat or electrical or burning energy to the skin is not a desirable way to achieve tightening.”

Other potential side-effects, which can occur after just one session, include scars and pitting, as well as hyperpigmentation, which is a particularly prevalent risk for people of colour.

Given that plasma pens you could use at home aren’t regulated by bodies such as the FDA — “The FDA is not aware of any legally marketed device of this kind,” says a spokesperson in a statement — there’s also little action you could take if you were negatively affected by the treatment.

Other healthcare professionals and institutions have previously released statements warning about the adverse effects of plasma pens. Back in 2019, Health Canada put out a warning about buying unauthorised pens and warned that the “likelihood and severity of side effects increase with the duration, frequency, and intensity of treatment”.