L-Threonine is an essential amino acid used in skincare as a hydrating and skin-conditioning agent, often as part of amino acid blends or natural moisturizing factor (NMF) complexes. It supports the skin's moisture balance and contributes to the protein structure of the skin barrier.
| Reported effect | How often | Notes |
|---|---|---|
| Mild irritation or stinging | Rare | Generally well tolerated; transient irritation may occur in sensitive skin. |
| Allergic contact dermatitis | Very rare | Isolated sensitivity reactions are uncommon for amino acids. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.
Peer-reviewed papers on this ingredient, via PubMed.