Efficacy and Facial Microbiome Modulation of 30% Supramolecular Salicylic Acid versus Topical Fusidic Acid in Mild-to-Moderate Acne Vulgaris: A Randomized Comparative Study

The skin is not merely a barrier; it is a living landscape teeming with microscopic life. Among the billions of bacteria that call the human face home, a few species dominate, including Cutibacterium acnes, which lives deep within hair follicles, and various staphylococci that reside on the surface. In a healthy state, these microbes exist in a delicate balance. However, when this ecosystem becomes unbalanced, it can contribute to acne, a common inflammatory condition affecting the vast majority of adolescents and young adults. For decades, doctors have treated this condition with topical antibiotics, medicines designed to kill the bacteria responsible for the inflammation. While effective, the widespread use of these drugs carries a hidden cost: the bacteria can learn to survive them, rendering the medicines less useful over time. This growing concern has pushed researchers to look for alternative treatments that can clear the skin without disrupting the microbial community or encouraging resistance. One such candidate is a form of salicylic acid, a well-known ingredient used to unclog pores, but delivered in a new, more stable format that might be gentler on the skin's natural inhabitants.

A team of researchers at Beijing Tongren Hospital set out to test whether this new approach could match the performance of a standard antibiotic without causing the same ecological disturbance. They conducted a randomized trial involving forty-six adults with mild to moderate acne. The participants were divided into two groups. One group received a treatment of thirty percent supramolecular salicylic acid, applied by a professional in a clinic every two weeks for a total of four sessions. This procedure involved applying the acid to the face, massaging it in, and then neutralizing it with water, followed by a cold compress to soothe the skin. The other group applied a topical antibiotic called fusidic acid twice daily at home for eight weeks. The study was designed to be blind regarding the assessment, meaning the doctors who counted the pimples and evaluated the severity of the acne did not know which treatment each patient had received. Over the course of two months, the researchers tracked the number of lesions, the overall severity of the condition, and the changes in the bacterial communities living on the participants' skin.

The results showed that both treatments worked well. By the end of the eight-week period, the number of acne lesions had dropped significantly in both groups. When the researchers compared the two, they found no clear difference in how well the salicylic acid worked versus the antibiotic. Both groups saw similar reductions in inflammatory bumps, blackheads, and whiteheads. The percentage of patients who saw a substantial improvement was comparable, with roughly half of the people in each group achieving a significant reduction in their total lesion count. The study also noted that the salicylic acid treatment was generally well-tolerated, though some patients experienced temporary dryness or redness, which resolved quickly with moisturizing. In one instance, a patient with a history of cold sores experienced a recurrence of the virus after the treatment, a known risk with chemical peels that highlights the need for caution in patients with similar histories.

Perhaps the most significant part of the study was the deep dive into the skin's microbiome. The researchers collected swabs from the skin at the beginning of the study and again at the four and eight-week marks. They analyzed the genetic material of the bacteria to see how the treatments changed the community of microbes. They looked for signs that the antibiotic was wiping out specific bacteria or causing a chaotic shift in the ecosystem, while the salicylic acid might have left the community more intact. The data did not support the idea that one treatment was better at preserving the natural balance of the skin than the other. Both treatments caused changes in the bacterial populations, but the magnitude and direction of these changes were statistically similar. The researchers found no evidence that the salicylic acid spared the microbiome more than the antibiotic did, nor did they find a specific pattern of bacterial change that clearly explained why the skin improved.

The study concludes that supramolecular salicylic acid is a viable, non-antibiotic option for treating mild to moderate acne, offering clinical results that are on par with a standard topical antibiotic. However, the researchers are careful to note that their study was not large enough to prove that the salicylic acid is definitively better at preventing antibiotic resistance or preserving the skin's natural ecosystem. The lack of a detectable difference in microbiome changes suggests that the benefits of the acid may come from its ability to unclog pores and reduce inflammation rather than from a unique ability to protect the bacterial community. While the findings support the use of salicylic acid as a reasonable alternative, the authors emphasize that larger, longer-term studies are needed to fully understand how these treatments affect the long-term health of the skin and the development of drug resistance. For now, the study offers a reassuring message: there are effective ways to treat acne that do not rely solely on antibiotics, even if the exact mechanism of how they interact with our microscopic neighbors is still being uncovered.