Acne

A meta-analysis of 3 randomized, double-blind, vehicle-controlled trials in 629 patients aged 11 to 49 found tretinoin microsphere gel 0.04% significantly reduced both inflammatory and noninflammatory lesions over 12 weeks versus vehicle. Tretinoin is a first-line acne treatment in major dermatology guidelines, with consistent results across formulations from 0.025% to 0.1%.

The 2020 Cochrane review (49 trials, 3,880 participants across the covered agents) found azelaic acid was the topical with moderate-quality supporting evidence, and a 2023 systematic review found lesion reductions comparable to topical retinoids with better tolerability in some trials. Typical courses run 12 weeks at 15 to 20%.

A randomized, double-blind, placebo-controlled split-face trial in 26 patients found five 40% glycolic acid peels at 2-week intervals significantly reduced acne lesions versus placebo, working better on blackheads and whiteheads than inflamed lesions. A 2018 systematic review of 12 RCTs (387 participants) found chemical peels including glycolic acid similarly effective for mild-to-moderate acne, but rated the trial quality very low to moderate.

The 2020 Cochrane review found salicylic acid trials for acne carried high risk of bias and imprecision, rating the evidence low certainty despite decades of use. Peel-format data are somewhat better: the 2018 BMJ Open systematic review (12 RCTs, 387 participants) found salicylic acid peels performed on par with glycolic and other peels for mild-to-moderate acne. It clearly helps comedonal acne in practice; the grade reflects trial quality, not absence of effect.

A systematic review of 12 RCTs found commonly used peels (glycolic, salicylic, Jessner's) are similarly effective and well tolerated for mild to moderate acne, though trial heterogeneity blocked pooling. A 2022 network meta-analysis estimated chemical peels produce roughly 40 percent effectiveness for mild to moderate acne, real but below oral and combination topical therapy. Peels are an adjunct to medical acne treatment, not a replacement.

A 2019 systematic review and meta-analysis of blue light (14 trials, 698 participants) found reductions in acne lesions but flagged that most trials were small, shorter than 12 weeks, and at high risk of bias. A 2023 meta-analysis of LED skin therapy found red and blue light each help, with combined red plus blue performing best, pooled across trials with a large overall effect. Reasonable for mild to moderate acne as an add-on; not a replacement for retinoids, benzoyl peroxide, or oral therapy.

A 2020 Cochrane review covering topical nicotinamide among other agents found the supporting trials had high risk of bias and imprecise results, so it could not conclude the ingredient works for acne. Small trials suggest 2 to 4% niacinamide reduces sebum and inflammation, but it should not replace proven acne treatments like retinoids or benzoyl peroxide.

A 2020 meta-analysis pooled 8 RCTs (450 patients) and found IPL can reduce inflammatory acne lesions, but the trials were small, short, and heterogeneous in device settings, and IPL is not part of standard acne guidelines. It may be a reasonable adjunct for someone already getting IPL for redness, not a primary acne therapy.

Retinol is widely marketed for breakouts by analogy to prescription retinoids, but well-controlled trials of retinol itself for acne are essentially absent from the literature. The 2021 systematic review of OTC retinol products found no trustworthy product-level evidence even for aging, its best-studied use. If acne is the goal, adapalene 0.1% (OTC in the US) and tretinoin have actual trial support.

Bakuchiol is sold in acne lines on the strength of its antibacterial and anti-inflammatory lab profile, but human data are minimal. A 2024 systematic review of 15 human bakuchiol trials, which included acne studies, found 12 of 15 were unblinded open-label studies without a control group. There is no vehicle-controlled RCT establishing bakuchiol as an acne treatment.

A 2022 open-label series of the HydraFacial Clarifying protocol reported clear or almost clear skin rising from 20 to 65 percent by investigator assessment across a treatment series, with good tolerability. The study had no control group and was industry-linked, so it cannot separate the device from regression to the mean or concurrent skincare. No RCT supports HydraFacial for acne, and suction-based facials can aggravate active inflammatory acne.