"When used in combination" is not a standalone skincare ingredient but a phrase describing how multiple actives or ingredients are formulated or applied together. The combined effects—and tolerability—depend entirely on the specific ingredients involved.
| Reported effect | How often | Notes |
|---|---|---|
Increased irritation or dryness | Common | Combining multiple actives (e.g., retinoids with exfoliating acids) can raise the likelihood of cumulative irritation. |
Erythema (redness) | Common | Layering potent actives may cause transient redness, particularly in sensitive skin. |
Reduced efficacy from ingredient incompatibility | Uncommon | Certain pairings can degrade or neutralize one another, lowering performance. |
Contact dermatitis | Uncommon | Higher exposure to multiple sensitizers may increase allergic or irritant reactions. |
Increased photosensitivity | Uncommon | Some combinations (e.g., acids plus retinoids) can heighten sun sensitivity. |
Severe barrier disruption | Rare | Aggressive combinations over time may compromise the skin barrier. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.
Peer-reviewed papers on this ingredient, via PubMed.