Ingredient Conflict Checker Simultaneous application of certain actives can lead to chemical degradation or profound barrier compromise. Ingredient 1 Retinoid (Tretinoin/Retinol) AHA/BHA (Glycolic/Salicylic) L-Ascorbic Acid (Vitamin C) Niacinamide Benzoyl Peroxide Copper Peptides Ingredient 2 AHA/BHA (Glycolic/Salicylic) Retinoid (Tretinoin/Retinol) L-Ascorbic Acid (Vitamin C) Niacinamide Benzoyl Peroxide Copper Peptides Analyze Interaction Status Details. Key Conflicts: Retinoids + AHA/BHA (High irritation risk). L-AA + Copper Peptides (Metal ion oxidation of Vitamin C). Benzoyl Peroxide + Tretinoin (Oxidation/degradation of Tretinoin, use at separate times).