Azelaic Acid for Melasma
Topical 20% azelaic acid appears to fade melasma about as well as, and in some trials better than, hydroquinone, but it is an off-label use backed only by preliminary-grade evidence. It works slowly and only alongside strict daily sun protection.
Why this grade7-layer evidence engine
We rate this Preliminary (B) because the efficacy signal is real and consistent but modest in quality. A 2023 systematic review and meta-analysis of six randomized trials (PMID 37457606, n=673) found azelaic acid may lower melasma severity (MASI) at least as much as hydroquinone, and a broader 2023 review (PMID 37550898) reported the 20% cream beat both vehicle and 2% hydroquinone.
Two older double-blind RCTs anchor the evidence: a 329-patient multicenter trial (PMID 1816137) showed roughly 65% good-to-excellent results, comparable to 4% hydroquinone and with no exogenous ochronosis, and a 155-patient trial (PMID 2528260) found 73% good-to-excellent versus 19% for hydroquinone. The grade stays at B because these pivotal trials were industry-funded (a soft conflict-of-interest flag) and no major melasma guideline formally ranks azelaic acid.
Regulators reinforce the off-label caveat: the US FDA approves azelaic acid only for acne and rosacea, and the UK NHS/NICE and US MedlinePlus describe the same two on-label uses, not melasma. Clinic sources (Mayo, Cleveland, Harvard) are cautiously supportive. Bottom line: a reasonable, ochronosis-free alternative to hydroquinone, but expect weeks-to-months for results and pair it with rigorous SPF50+ sun protection.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.582
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (1 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status