Acne vulgaris might as well be called acne universalis. Research suggests that the condition strikes 85% of adolescents and young adults, and pimples can stick around long into adulthood.
Traditional treatments like benzoyl peroxide (BP) and isotretinoin remain important parts of the dermatologist's armamentarium, but other drugs have begun to play a role, too. Meanwhile, research is offering new insight into the causes of acne.
In the big picture, one dermatologist believes, there's no reason why anyone should suffer from acne.
"You don't have to have acne today. There are therapeutic approaches to keep patients acne-free," says Wilma F. Bergfeld, M.D., F.A.A.D., of the Cleveland Clinic, Cleveland, Ohio.
Here's a look at the pathogenesis, evaluation and treatment of acne.
As a 2011 report notes, there are four main factors believed to cause acne: Excess sebum production, growth of cutibacteria (now called Cutibacterium acnes, formerly known as Propionibacterium acnes or P. acnes), follicular hyperkeratinization (a hair follicle disorder that causes blockage in ducts), and inflammation.1
However, "there is so much more to acne" than these "classic four steps of pathogenesis," says dermatologist Andrea L. Zaenglein, M.D., of Penn State/Hershey Medical Center. "It is really a complex and multifactorial immune response where all of these factors are enmeshed and influenced by both genetic and external factors."
Researchers suspect that certain kinds of food boost the risk of acne. But studies into foods like chocolate and milk have tended to be small and conflicting. In general, healthier, lower-glycemic index foods — those that aren't high in sugar, fat and carbohydrates — are thought to be better for patents with acne.
"Most dermatologists are aware that diet and nutrition influence acne, but the role that they play is still being figured out," says Dr. Zaenglein, president-elect of the American Acne and Rosacea Society. "Other than general good nutritional advice, specific food eliminations cannot be recommend based on available data."
Dr. Bergfeld adds that hormone dysfunction can play a role in acne pathogenesis too. Polycystic ovary syndrome, for example, can cause acne along with other conditions.
Colleagues should focus on more than individual pimples, says Robert P. Dellavalle, M.D., Ph.D., M.S.P.H., University of Colorado School of Medicine, Colorado School of Public Health and VA Eastern Colorado Health Care System.
"A lot about acne severity has to do not only with how many lesions are present and how big and nasty they are, but whether the disease is getting better or worse," he says.
One evaluation strategy is to rely upon a scale of acne severity. As the American Academy of Dermatology noted in its 2016 guidelines co-written by Dr. Zaenglein, "clinicians may find it helpful to use a consistent grading/classification scale (encompassing the numbers and types of acne lesions, as well as disease severity, anatomical sites, and scarring) to facilitate therapeutic decisions and assess response to treatment."
While the academy declared that "currently, no universal acne grading/classifying system can be recommended," it did point to a 2013 report that identified "highly ranked" acne global grading scales.
A later critique and review of scales published in 2016 noted "poor overall performance of most scales, largely characterized by the absence of reliability testing or evidence for independent assessment and validation indicates that generally, their application in clinical trials is not supported."2,3
The academy guidelines noted that "improvements in digital technology, photographic equipment, and teledermatology may allow for accurate, remote assessment of acne in the near future. Scientific measures, such as ultraviolet-induced red fluorescence, casual sebum level, skin capacitance imaging, kin surface pH, and transepidermal water loss may also help to more objectively classify and rate acne in the future."
As for testing in acne, the academy recommends against routine microbiologic testing, although it may be useful in patients "who exhibit acne-like lesions suggestive of gram-negative folliculitis."
The academy also recommends against endocrinological testing unless patients show additional signs of androgen excess.
Dr. Bergfeld is a fan of thyroid tests for patients with acne. She says tests for testosterone and the adrenal hormone dehydroepiandrosterone (DHEA) may also be appropriate. Birth control pills and even adrenal suppression may be useful in certain patients with hormonal abnormalities, she adds.
"Commonly used topical acne therapies include BP, salicylic acid, antibiotics, combination antibiotics with BP, retinoids, retinoid with BP, retinoid with antibiotic, azelaic acid, and sulfone agents," the American Academy of Dermatology notes in its 2016 acne guidelines.
In regard to topical drugs, benzoyl peroxide is "an excellent treatment" and continues to be an effective tool to dry up lesions, Dr. Bergfeld says.
According to the academy, other helpful topical tools include retinoids, azelaic acid (as an adjunct in postinflammatory dyspigmentation) and dapsone 5% gel (in inflammatory acne, especially in adult females).
However, the academy notes, "there is limited evidence to support recommendations for sulfur, nicotinamide, resorcinol, sodium sulfacetamide, aluminum chloride, and zinc in the treatment of acne."
Dr. Bergfeld says the key is not to be too zealous with topical therapies. You don’t want to overdry the skin.
The American Academy of Dermatology also says topical and systemic antibiotics can be helpful in moderat-to-severe acne and resistant inflammatory acne, but it cautions against their solo use because of the risk of antibacterial resistance.
The guidelines advise against use for more than three months and suggests they’re used "with a topical retinoid and BP [benzoyl peroxide]. Evidence supports the efficacy of tetracycline, doxycycline, minocycline, trimethoprim/sulfamethoxazole (TMP/SMX), trimethoprim, erythromycin, azithromycin, amoxicillin, and cephalexin."
Dr. Dellavalle is an advocate of less antibiotic use, and he prefers alternatives such as spironolactone, retinoids, benzoyl peroxide and light therapy.
Birth control pills are a good option for women, Dr. Zaenglein adds.
"They are an FDA-approved treatment for acne and yet only about 50% of dermatologists prescribe them,” she says. “Most of the time when I speak on this, I hear they were just not trained on their use. However, sending females to the gynecologist results in significant delays in care and added costs."
Another systematic treatment is isotretinoin, which is powerful but has a history of side effects. The American Academy of Dermatology recommends its use with appropriate cautions in severe nodular acne and "moderate acne that is treatment-resistant or for the management of acne that is producing physical scarring and/or psychosocial distress."
Hopefully, Dr. Zaenglein says, "dermatologists are moving on to isotretinoin sooner in patients that are not responsive to other treatments." She adds, based on research findings, "I would advocate for using a topical retinoid after — or even concomitantly with — isotretinoin to help minimize scarring."
As for complementary and alternative treatments, the American Academy of Dermatology's guidelines say they mostly seem to be well-tolerated, but "very limited data exist regarding the safety and efficacy of these agents to recommend their use in acne."