At some point over the course of the past year, rolling your face with itty-bitty needles in the name of #selfcare has very much become a thing. Microneedling (AKA “derma rolling”) went from your dermatologist’s office to your Instagram feeds to your actual bathroom, and I personally can’t remember what life was like without my favorite spiky little tool (aside from being far, far less glowy).

But this morning, after using mine religiously for the last 18 months, I found out that I’d been doing it wrong the entire time—which, understandably, left me with a whole lot of questions about how to actually use a dermaroller.

Dermarollers—which admittedly look like some form of medieval torture device, but happen to feel amazing—use small, sharp points to stimulate tissue regeneration and help your topical products penetrate better. Because of this, I’d always assumed that sandwiching my prickly mini-facial in between my toner and serums made the most sense. As it turns out, though, in doing so I was actually putting my skin at risk for a rash. According to a new study, microneedling after you’ve put on any products can introduce “immunogenic particles” into the skin, which can cause allergic and hypersensitive reactions.

Um, whoops.

The right time to dermaroll is “after washing [and] before applying topical products onto clean skin.” —Rachel Nazarian, MD

With that in mind, Dr. Rachel Nazarian of Schweiger Dermatology says that the right time to dermaroll is “after washing [and] before applying topical products onto clean skin.” Even if you’re doing it in the right order, though, it’s still important to be aware of the types of products you’re using alongside the device. “Ingredients that are irritating to skin will be more likely to inflame your skin after dermarolling and can dry it out faster or cause itching and redness,” she says. “Everything works more potently with a dermaroller, so I would avoid alcohol-based products such as toners or essences which are not meant to have deep penetration into skin, and can be quite intense if used after this procedure. Those should be used on intact skin.” She also advises staying away from sunscreen and makeup post-dermaroll, which means you should probably make your needle facial a part of your evening routine instead of your a.m. one.

A few potions that do have the derm green light to use in tandem with a dermaroller? Moisturizers, lotions, serums, and peptide or growth factor-based products—AKA anything hydrating, which you want to absorb deeply into your skin in order to give it some added glowy goodness.

As with any aspect of your skin-care routine (especially one that, ya know, involves needles), it’s important to listen to your skin. “If it’s getting very red, hot, irritated, decrease usage and minimize the products you’re applying afterwards,” says Dr. Nazarian. “Always use a clean dermaroller and on a freshly cleansed face—you don’t want to introduce bacteria or fungus into your skin and cause a skin infection.” No, no I do not.

Find out what happened when our beauty editor tried dermarolling for a week, and if you’re thinking of testing it out yourself, pair the process with one of these ultra-hydrating serums.