Threonine is an essential amino acid used in skincare primarily as a humectant and skin-conditioning agent, helping support hydration and the skin's natural moisturizing factor. It is also a building block for proteins such as collagen and elastin.
| Reported effect | How often | Notes |
|---|---|---|
| Mild irritation or stinging | Rare | Generally well tolerated; transient irritation possible in sensitive skin. |
| Allergic contact dermatitis | Very rare | Isolated sensitization reactions reported, 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.