Theanine (L-theanine) is an amino acid derived primarily from tea leaves, used in topical formulations for its antioxidant and skin-soothing properties. In skincare it is included to help mitigate oxidative stress and support a calming effect on the skin.
| Reported effect | How often | Notes |
|---|---|---|
Mild skin irritation or redness | Rare | Generally well tolerated topically; transient irritation possible in sensitive individuals. |
Contact allergic reaction | Very rare | Allergic sensitization is uncommon but theoretically possible with any topical ingredient. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.