Zinc for Acne
Oral zinc shows a real but modest signal for inflammatory acne, yet the evidence is weak and inconsistent, and no major dermatology authority recommends it as a treatment. It may have a supporting role for some people, but it does not replace standard therapies and effective study doses exceed safe supplement limits.
Why this grade7-layer evidence engine
This claim earns a Weak (C) grade because the positive findings are genuine but limited. A systematic review and meta-analysis (PMID 32860489) found oral zinc reduced inflammatory papules (SMD 0.73, 95% CI 0.339-1.122) and that acne patients had lower serum zinc, but it pooled observational studies with RCTs and did not separate oral from topical forms. An open-label RCT (PMID 34188751) reported zinc sulphate was non-inferior to the antibiotic lymecycline, though its unblinded design and subjective scoring weaken confidence.
Crucially, when zinc is ranked against other treatments it falls short. The largest acne network meta-analysis (PMID 37487721) placed zinc monotherapy below first-line antibiotics and retinoids, and an older head-to-head trial (PMID 11586012) found minocycline outperformed zinc. This is why the grade stays low despite the favorable individual studies.
Authorities reinforce the caution. The American Academy of Dermatology's 2024 guideline explicitly makes no recommendation for or against zinc for acne, citing insufficient evidence; Cleveland Clinic calls it only a possible adjunct, while NHS, EFSA, and WHO endorse zinc for immunity and childhood diarrhea, not acne. Effective trial doses (about 90-100 mg elemental zinc) far exceed safe supplement ceilings and risk copper deficiency, so any use belongs under medical supervision.
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 = 0.474
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status