It’s no secret that hormonal shifts (puberty, menopause) can bring on breakouts, but there are a bunch of other acne triggers that can cause sudden acne breakouts to surface seemingly overnight. It typically comes down to one of three things, insists Jerry Tan, M.D., adjunct professor of dermatology at the University of Western Ontario and an Acne Store advisory board member: “What's happening on the surface of your skin, what’s happening internally, and what's happening in your life.” Keep reading to discover six stealthy culprits that could be behind an unexpected crop of pimples.

1. Stress can cause sudden breakouts

Not to stress you out, but stress itself causes acne breakouts, says Tan. Research backs this up: A 2017 study in Clinical, Cosmetic, and Investigative Dermatology finding that university students under stress had more pimples than those who were more stress free. [1] Stress can also impact the amount and quality of the sleep you get—and if you’re lacking, it can be bad news for your skin. “Sleep is critical to reducing some of the inflammatory mediators that are part of our day-to-day life,” says Tan. And since inflammation is involved in the formation of acne, it only makes sense that missing out on sleep can bring on those bumps. One 2015 study found that acne was linked to feelings of fatigue upon waking (a sign of shut-eye deprivation). [2]

2. Your hair products could cause acne

“Typically, when I see acne on the side of the neck or on the back and shoulders that corresponds to the length of that person's hair, it tips me off that a product could be making that patient break out,” says Tan. Often, a heavy conditioner or grooming products such as hairspray or holding gels are to blame. Swap conditioners and see if that helps and sleep with your hair up and away from your face in a scrunchie or soft, not-too-tight ponytail holder.

Acne comes down to three things: What's happening on the surface of your skin, what's happening internally, and what's happening in your life.

3. Medications can be a culprit

Some prescriptions can bring on breakouts by messing with your body chemistry, according to Tan. Among them: certain anti-seizure medications and lithium. He’s also seen this happen with hormonal IUDs, “Although the theory behind IUDs is that the hormones are only circulating within the reproductive system, it seems to be a much more systemic reaction in some women,” he says.

And it’s not just about what drugs you’re on—going off some medications can trigger sudden acne breakouts too. “In some women, birth control pills suppress breakouts, and going off them has the opposite effect.,” Tan explains. “Their hormones are no longer being regulated by the Pill, allowing oil production to run amuck and trigger acne.”

4. Skincare products can also cause breakouts

Although brands have gotten better over the years at formulating products to be non-pore-clogging, not all are—even when they’re labeled that way. “Looking for those words is a good start, but in reality, you're your own best tester,” says Tan. “And sometimes your skin just won’t like a particular product.” That’s why it’s important to make note of any changes to your skincare routine preceding a sudden pimple outbreak. “Anything new that you may have applied on the area where the breakouts are occurring, whether it's a makeup product, a moisturizer, or a sunscreen, may be a trigger,” says Tan. These products can mix with oil and debris on your skin and cause sudden acne breakouts on the face. If you have added something to your routine just before an acne flare, eliminate it for a few weeks and see if your skin clears up. If it does, you’ve likely found the source of your newfound acne.

5. Your diet may also be to blame

“What you eat is a really important component that we haven't really spent enough time researching until the last five years or so,” says Tan. While we don’t yet know everything that can impact the clarity of skin, there are two major sources science has pinpointed so far that can cause sudden acne: Dairy products and foods that are high on the glycemic index scale. “These lead to hormonal changes that trigger oil glands to produce more oil,” Tan explains.

So, what is a high glycemic index food? “They tend to be processed, high in sugar, and release their sugar content rapidly,” says Tan. Think fast food, white bread, and sweets. And, yes, cutting back on them if you’re breaking out can be a good idea. A 2018 study in the Journal of the Academy of Nutrition and Dietetics showed that just two weeks of a low-glycemic diet reduced concentrations of IGF-1, an acne risk factor. [3]

As for dairy, a 2018 research review in the journal Nutrients concluded that dairy intake, including milk, yogurt, and cheese, was associated with increased acne breakouts (although the authors cautioned that more research needs to be done). [4] As for why this might be, Tan explains that it’s thought that milk derived amino acids may spur on the release of insulin and IGF-1, which in turn increases androgen hormones that can trigger sudden breakouts of acne.

6. Yes, even supplements can cause acne

You may think you’re doing your body good with supplements, but some of them can cause pimples. “Protein supplements may be a problem because whey protein, which is derived from dairy, has been shown to trigger acne in predisposed individuals.” A small Brazilian study of 30 people backs this up—and it all goes back to dairy, where the whey comes from. [5] “Whey protein increases the amount of insulin released from the body, and that insulin acts on your skin’s oil glands, triggering them into production,” says Tan. The result in some cases: A sudden acne breakout on the face. “I tell my patients who want to take protein supplements—OK, but no whey,” he adds.

References:

[1]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5722010/

[2]: https://pubmed.ncbi.nlm.nih.gov/25365961/

[3]: https://pubmed.ncbi.nlm.nih.gov/29691143/

[4]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115795/

[5]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900340/