Acne is the most common skin condition in the United States – it affects about 50 million faces a year, according to the American Academy of Dermatology. But it is also one of the most complicated, as its causes and effective treatments seem to differ from person to person.

Any high school student with an internet connection knows that papules, pustules and blackheads start to form when dead skin cells and oils clog the tiny hair follicles that cover the face and upper body . This creates the perfect space for a common microbe, C utibacterium acnes , to settle. But only a few clogged pores become red and swollen pimples. This happens when our own immune cells precipitate, triggering inflammation. Even for dermatologists, the intricacies of this immune response are still unclear or under control.

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Traditionally, doctors think of acne as a chronic skin condition, like psoriasis, with its scaly or rosacea rash, which causes redness and swelling on the face. But, in a new article published last Thursday (26) in Trends in Immunology , a team of Hungarian scientists argues that acne is more like orthodontic appliances or invitations to graduation parties: a “natural transient inflammatory state” , ostensibly important for the development of adolescents . Using existing research on animal models, experiments on human skin samples and genetic data, the researchers conclude that it all comes down to age-related changes in the skin microbiome .

Most people spend their childhood with flawless skin, but something changes with puberty. Specifically, the sebaceous glands. These microscopic bags, attached to the hair follicles, pump oil to keep the skin lubricated. Although they provide a shiny appearance throughout our lifespan, the glands are particularly aggressive at puberty, when our systems are flooded with androgenic hormones, which stimulate sebum production among other transforming functions.

The authors argue that this oil production in adolescence provides lipophilic microorganisms (literally fat lovers), such as C. acnes , with the necessary fuel to dominate their environment. But it is not just any C. acnes that proliferates: recent genomic evidence indicates that the bacterium exists in many different varieties, some of which are beneficial and others more likely to trigger inflammation. When it feels that the microbiome is out of control, the immune system then rushes into battle, messing with the skin in the process.

“In fact, it’s a very interesting proposition about why we have acne,” Suzan Obagi, professor of dermatology at the University of Pittsburgh Medical Center and director of the UPMC Skin Health and Plastic Surgery Center, told Gizmodo. “One of the things that we are realizing more and more is the importance of this balance between human beings and the microbiome”.

Those years of oily teenage skin don’t last forever, of course. Sebum production naturally decreases as the puberty period passes. The researchers think this explains why 85% of teenagers suffer from acne, but 50% of these cases are resolved spontaneously. Although it may be a physically and psychologically traumatic condition , the article speculates that acne may be a learning experience for the immune system, which leads to the crystalline skin we expect from adulthood. Except… that’s not always how it works.

“I don’t agree with the transitory element,” said Adam Friedman, a dermatologist at the George Washington University School of Medicine and who was not involved in the new article, to Gizmodo. “As a practicing dermatologist, the number one patient I receive is an adult, not a teenager.”

While some people can overcome acne apparently overnight, many patients need a skin care regimen or prescribed treatments to keep pimples at bay between 20 and 30, and in some cases, even 40 and over. 50 years. “I think a lot of people underestimate acne,” said Friedman. “It can have lasting implications”, including scarring and discoloration.

Other dermatologists were skeptical about the article’s emphasis on sebaceous glands, perhaps excluding other important pathways. Whitney High, a dermatologist at the University of Colorado who was not affiliated with the research, told Gizmodo that the article ignores the crucial role of hormones, which can alternately aggravate or relieve acne, especially in women . And Friedman noted that recent research showing that C. acnes can produce short-chain fatty acids that disrupt immune regulation in sebaceous cells was absent in the study. (Andrea Szegedi, the article’s corresponding author, declined to comment on this story.)

“This is a very hot topic,” said Friedman. Traditionally, doctors prescribe patients with acne retinoids, salicylic acid and systemic antibiotics like tetracycline.

In recent years, however, dermatologists have realized that their field is a major contributor to antibiotic resistance , in part because people with acne often take antibiotics for months or even years. But the growing recognition that acne is caused, at least in part, by a broken microbiome (and not, as popular mythology says, by fatty foods or poor hygiene) means that some doctors are changing course.

Instead of destroying bad bacteria, Friedman said, they want to restore what is good. He described modern approaches designed to combat acne, helping the skin’s microbiome to maintain balance, like probiotics , made from living microorganisms that encourage the growth of beneficial and prebiotic bacteria and fungi derived from food compounds that serve a similar objective. These solutions “are still premature,” said Friedman, but the message is clear: you can teach old skin new tricks.

Even with acne treatments becoming more sophisticated, scientists still cannot fully understand it. And much to the chagrin of those who suffer from pimples all over their bodies, it does not appear that an infallible cure is about to be discovered.