Glutathione for Skin Health
Oral glutathione is marketed for skin whitening, but the evidence does not support it: any effect is modest, limited to sun-exposed areas, and disappears once you stop. Injectable "whitening drips" have no proven benefit and carry real safety risks.
Why this grade7-layer evidence engine
The grade reflects a small, low-quality, and contradictory evidence base. The two systematic reviews disagree: one found oral glutathione lowered the melanin index versus placebo but called the effect "moderately efficacious but unsustainable" (PMID 39444151), while a 2019 review reported brightening only in sun-exposed skin, none in sun-protected areas, and concluded the whitening effect is "inconclusive" (PMID 30895708). The single placebo-controlled RCT (n=60, 4 weeks) reached significance at only two of six body sites (PMID 20524875).
The highest-quality appraisal is the most negative: a 2020 evidence-based review judged glutathione "not beneficial enough" as a whitening agent because it worked only in some areas and produced no lasting effect (PMID 32373172), and a critical review framed the practice as largely myth-leaning with limited support (PMID 27088927). A core problem is that oral glutathione is poorly absorbed, since the tripeptide is broken down in the gut, undermining any systemic effect. All studies were small, short, and of undisclosed funding.
Regulators and clinics offer no support. The US FDA has never approved glutathione for skin lightening and warned that supplement-grade powder used in injectable "whitening" drips was contaminated with bacterial endotoxin; UK authorities call cosmetic IV glutathione dangerous and illegal. Major clinics (Mayo, Cleveland Clinic, Harvard) and dermatology bodies do not endorse it. The most evidence-based step for skin tone remains daily broad-spectrum 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 = 0.452
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- 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