Welcome to Ask a Derm, a series from SELF in which board-certified dermatologists answer your pressing questions about skin, hair, and nail health. For this installment, we tapped Susan C. Taylor, MD, the Bernett L. Johnson Jr. Endowed Professor of Dermatology and the vice chair for diversity, equity, and inclusion for the department of dermatology at the University of Pennsylvania’s Perelman School of Medicine. Her specialties include hair loss, cosmetic dermatology, hyperpigmentation, and skin of color.

One of the golden rules of skin care: Never pop your pimples. Of course, it’s tough advice to follow if that angry bump is just sitting there, taunting you—and even harder when you do leave it alone and still end up with a hard-to-ignore dark spot.

In case you didn’t know, picking your acne causes trauma to your skin, which can lead to scarring and hyperpigmentation. That’s why pretty much every derm out there will beg you to keep your hands (and extraction tools) off your face. If you’re anything like me, though, you know from experience that leaving your pimples alone isn’t a foolproof solution: Even when I summon the willpower to let a zit run its course, I’m sometimes still left with a flat red or brown mark in its place. To figure out why this happens, I called in the help of a pro.

Basically, the buildup—of excess oil, dead skin cells, and sometimes bacteria—that causes acne can trigger an inflammatory response, Susan C. Taylor, MD, professor of dermatology at the University of Pennsylvania’s Perelman School of Medicine, tells SELF. During this process, your body releases pigment-producing melanocytes (the cells responsible for your skin’s color) to protect the affected area, Dr. Taylor says.

Thanks to this awesome immune response, you may notice smaller, surface-level blemishes like whiteheads and blackheads resolve on their own—without leaving a mark. But let’s say you’re dealing with more severe inflammation (from angrier, deeper cystic acne that has lingered for months, or even a nasty bug bite). In that case, your body might overreact and pump out lots of (and sometimes too much) protective melanin. “This can cause post-inflammatory hyperpigmentation,” Dr. Taylor explains—a.k.a. brownish or blue-gray spots that remain even after the blemish has healed.

Not everyone is doomed to get PIH. Some people have a higher chance of developing the condition, including folks with darker skin tones (like those of African or Asian descent), Dr. Taylor says. Compared to people with fairer skin, these groups have more melanin to begin with (that’s why their complexion is darker)—“so they’re also more likely to overproduce melanin in response to inflammation,” she says.

Sun exposure, too, can cause your body to release extra melanin in an effort to protect your skin against UV damage. This can make your existing blemish even more pigmented and also increase your risk of developing PIH after it heals.

Now, you might be thinking: If I’m going to get a dark spot anyway, why not pop this sucker and just get it over with? Here’s a very good reason to resist that urge: “You could make your mark even darker, larger, wider, and overall worse,” Dr. Taylor warns. Plus, squeezing the area with your fingers can potentially create an open wound and up your chances of getting an infection.

As stubborn (and obvious) as post-pimple dark spots can be, the good news is that they typically do go away, or at least lighten up. It just takes time (several months is the norm, per Dr. Taylor)—but there a few OTC treatments that can help them fade faster. Most notably, you should look for skin care products with brightening ingredients like vitamin C, licorice, and tranexamic acid. And if you’re currently stuck with an angry zit that you know will leave a lasting impression, Dr. Taylor recommends applying a cool compress to the spot. This can help speed up the healing process by reducing inflammation, which in turn lowers the possibility of melanin overproduction.

Unfortunately there isn’t much else you can do to completely prevent hyperpigmentation. But according to Dr. Taylor, the closest thing to a “solution” is sun protection. Being diligent about applying SPF every single day, she says, is your best bet for keeping new spots from forming—and fading any you already have.

Related:

• Can My Dry Lips Actually Become ‘Addicted’ to Lip Balm?
• Just 12 People Proudly Sharing Unfiltered, Makeup-Free Pics of Their Acne
• How to Deal When You’re Having a Bad Skin Day

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