Bioflavonoids

Bioflavonoids (a broad class of plant-derived polyphenols such as rutin/quercetin derivatives) are typically used at low concentrations for antioxidant/soothing support and are generally well tolerated on skin. However, because they are botanical extracts/actives with variable composition and occasional reports of contact dermatitis in highly reactive or eczema-prone patients, they carry a small but real irritation/sensitization risk. I score them as gentle rather than very gentle to reflect that variability and to prioritize safety in compromised skin. Safety Notes: In mass-market leave-on products (toners/serums/creams) “bioflavonoids” are often part of botanical or citrus extract systems and appear at very low labeling-relevant levels (~0.001–0.05%) where the extract is used mainly for antioxidant/soothing claims and color/odor constraints limit higher use. Dedicated antioxidant/brightening formulas and some consumer-available high-strength serums use enriched bioflavonoid complexes typically around 0.1–2%, with a small number of niche products pushing to ~3–5% total bioflavonoids in the active blend (higher levels are uncommon due to solubility, staining/yellowing, and increased irritation risk). Rinse-off products generally sit at the low end (often ≤0.1%) because of short contact time, while the highest concentrations are primarily seen in leave-on treatments.