Acne: It's not contagious and other things dermatologists want you to know

Acne is so common in young people — affecting 85% of teenagers according to the American Academy of Dermatology — that it is practically a rite of passage. And it’s not rare in adults, affecting 12% of women and 3% of men, according to one study.

Despite that, the skin condition remains widely misunderstood, doctors say. Case in point: Half of acne-free adults in a recent small study incorrectly said it was contagious and even more said, also incorrectly, that it is caused by poor hygiene.

“It’s clear from this study that we have quite a bit of education to do,” says Alexa Boer Kimball, a professor of dermatology at Harvard Medical School. She presented the study, which included 56 adults, at a recent meeting of the dermatology academy.

Even doctors may need an acne update, because treatment has evolved in recent years, say experts who worked on updated treatment guideline published in February in the Journal of the American Academy of Dermatology.

So here are a few things the experts would like everyone to know:

You can’t wash acne away.

“Acne is not about dirt. It’s about inflammation,” Kimball says. So while it’s certainly a good idea to wash your face, “you don’t want to overdo it,” she says. Hard scrubbing with a wash cloth or abrasive cleansers can irritate the skin and make effective treatment more difficult, says Bethanee Schlosser, an assistant professor of dermatology at Northwestern University Feinberg School of Medicine in Chicago. She worked on the treatment guidelines.

Pimples don’t pop up overnight.
While it can seem that way, the skin blemishes you see are the result of processes that can take a couple of months, as dead skin cells, oil and bacteria accumulate in pores, Schlosser says. That’s why trying to deal with pimples as they arise is a losing battle, she says. Instead, you need a daily regimen that prevents new blemishes.

Drugstore products really might help — but there’s a catch. 
The catch is that despite the many different products — and ads for those products — the vast majority are built around just two active ingredients: benzoyl peroxide and salicylic acid. They come in varying strengths and in many different formulations, including creams and cleansing cloths, but “they are all variations on a theme,” Schlosser says. Benzoyl peroxide works by killing bacteria. Salicylic acid helps exfoliate dead skin cells. “They do work to some extent for some patients,” especially those with fairly mild acne, Schlosser says. They also can be used in combination with prescription medicines.

Big-gun treatments must be used with care.
If you have moderate to severe acne and seek medical help, you may well be prescribed oral medicines in addition to topical treatments (the medications you apply directly to your skin). Those oral medicines can include antibiotics — and, if you have been paying any attention to health news in recent years, you know there’s a lot of worry about overusing such drugs and creating drug-resistant strains of bacteria. Antibiotics also can come with side effects such as diarrhea, vaginal yeast infections and allergic reactions. “In the past it would not be uncommon for people to be on antibiotics for years for acne,” but now the academy is urging doctors to limit use to about three months in most cases, says treatment guideline co-chair Andrea Zaenglein, a professor of dermatology and pediatric dermatology at Penn State’s Hershey Medical Center in Hershey, Pa. Another big-gun treatment, isotretinoin (first sold as Accutane, a now discontinued brand), also comes with risks: It can cause birth defects, so female users are required to take steps to avoid pregnancy.

Diet might matter.
Contrary to popular belief, greasy foods and chocolate do not cause acne, the experts say. But some science does link acne with “high glycemic” diets —  diets that include a lot of sugar, white bread, white rice and other highly processed foods. And several studies looking for a link between dairy foods and acne have turned up a puzzling finding: if there is a link, it might be strongest for skim milk. “Right now, we don’t have enough quality data to make any sweeping recommendations,” Schlosser says. It would be especially unwise to suggest teens not drink milk, Zaenglein says: “Teenage girls, especially, need to build up their bone density, and milk is often a source of vitamin D and calcium.”  But, she says, a diet lower in sugar and highly processed foods would be healthier overall for many people.