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Head-to-head evidence comparison — which supplement is right for you?
Glycolic Acid vs Niacinamide: they're closely matched on evidence (6 vs 6/10); they're alternatives for even skin tone — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Glycolic Acid and Niacinamide are closely matched across evidence, studies, and safety.
Verdict
Too few graded studies
Top outcomes
Verdict
Too few graded studies
Top outcomes
Shared outcomes (2)
Outcomes where both Glycolic Acid and Niacinamide have evidence — compare verdict strength side-by-side.
Topical cosmetic only. Leave-on glycolic acid is used at roughly 5-15% in lotions/serums (often at low pH), applied to clean skin a few nights per week and building as tolerated; professional peels (20-70%) are applied in-office at intervals. There is no oral, injectable, or systemic dose — it is not ingested. Pair with daily sunscreen. This library does not provide an ingestion protocol.
Evening
Leave-on lotion or serum (≈5-15% glycolic acid)
Topical cosmetic only. Niacinamide is typically formulated at 2-5% in leave-on serums, creams, or gels and applied to clean skin once or twice daily (AM and/or PM). It layers well under sunscreen and with most other actives. There is no oral, injectable, or systemic dose in this cosmetic context — it is not ingested here. This library does not provide an ingestion protocol.
Any time of day
Leave-on topical serum or cream (2-5% niacinamide)
Throughout
8-12 weeks
8-16 weeks
First weeks
Throughout
4-12 weeks
2-12 weeks
2-8 weeks
A double-blind randomized clinical trial on the effectiveness of a daily glycolic acid 5% formulation in the treatment of photoaging.
Dermatol Surg (1998) · Rct · n=75
75 volunteers applied 5% unneutralized glycolic acid cream or placebo to face and neck daily for 3 months (double-blind, randomized, placebo-controlled)
Clinical improvement of photoaged skin with 50% glycolic acid. A double-blind vehicle-controlled study.
Dermatol Surg (1996) · Rct · n=41
41 volunteers received a 50% glycolic acid peel vs vehicle weekly for 4 weeks (in-office peel strength)
Mode of action of glycolic acid on human stratum corneum: ultrastructural and functional evaluation of the epidermal barrier.
Arch Dermatol Res (1997) · Open label
Electron-microscopy study of human skin after 3 weeks of 4% glycolic acid twice daily
Niacinamide: A B vitamin that improves aging facial skin appearance.
Dermatol Surg (2005) · Rct · n=50
Double-blind, left-right randomized split-face design: 5% niacinamide vs vehicle applied twice daily for 12 weeks in 50 white women with facial photoaging
The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer.
Br J Dermatol (2002) · Rct · n=18
Paired clinical trial: 18 subjects with hyperpigmentation used 5% niacinamide vs vehicle moisturizer (plus a separate facial-tanning arm)
A Double-Blind, Randomized Clinical Trial of Niacinamide 4% versus Hydroquinone 4% in the Treatment of Melasma.
Dermatol Res Pract (2011) · Rct · n=27
Split-face RCT in 27 melasma patients: 4% niacinamide vs 4% hydroquinone (HQ) for 8 weeks, both with sunscreen
Both Glycolic Acid and Niacinamide are closely matched — the best choice depends on your specific health goals.
For even skin tone, Niacinamide has a higher relevance score (75 vs 60).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
AM/PM order, what to combine vs separate, and why sunscreen always comes first.
The proven core (sunscreen, retinoids, vitamin C) vs the viral hype tier — honestly tiered.
The depigmenter playbook (hydroquinone, azelaic, tranexamic, vitamin C) with sunscreen as the spine.
Benzoyl peroxide & retinoids → salicylic/azelaic/niacinamide → naturals, tiered by evidence.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.