Compare Supplements

Topical OTC use. Benzoyl peroxide is used at 2.5-10% in gels, creams, and washes, applied to acne-prone areas once or twice daily; lower strengths (2.5-5%) are usually as effective as 10% with less irritation. There is no oral or systemic dose — it is not ingested. It is often combined with a retinoid (e.g. adapalene) for greater effect. This library does not provide an ingestion protocol.

Any time

Leave-on gel/cream (2.5-5%) or a fixed combination with a retinoid

Topical cosmetic only. L-ascorbic acid serums are typically 10-20% (often near pH 3 for absorption); stable derivatives are used at varying percentages. Apply a few drops to clean, dry skin, usually in the morning under sunscreen (its antioxidant action complements SPF). There is no oral, injectable, or systemic dose in this cosmetic context. This library does not provide an ingestion protocol.

Morning

Leave-on topical serum (10-20% L-ascorbic acid) or a stable vitamin C derivative

• For topical (skin) use only — not for ingestion, not for injection
• Known allergy/sensitivity to benzoyl peroxide (true allergic contact dermatitis is uncommon but possible)
• Application to broken, severely inflamed, or sunburned skin until healed

• Topical retinoids degraded by oxidation (some tretinoin formulations)
• Other irritating actives (acids, other retinoids)

• For topical (skin) use only — not for ingestion, not for injection (in this cosmetic context)
• Known allergy or sensitivity to the formulation
• Application to broken, irritated, or compromised skin until healed

• Strong leave-on actives (retinoids, AHAs/BHAs, benzoyl peroxide)
• Niacinamide