This review analyzed 49 clinical trials testing six common acne ingredients (azelaic acid, salicylic acid, niacinamide, sulfur, zinc, and alpha-hydroxy acids) on nearly 3,880 people. Most participants had mild to moderate acne and were treated for over 8 weeks, but the abstract doesn't specify which ingredients actually worked best—the full results section was cut off.

Researchers searched multiple medical databases through May 2019 and only included randomized controlled trials (the gold standard) that compared these six topical treatments against each other, placebos, or no treatment. They measured how much acne improved, side effects, and quality of life impacts.

Funding not disclosed in abstract