Lysine is an essential amino acid used in skincare primarily as a skin-conditioning and humectant-like ingredient, and as a component supporting collagen and protein structure. It is generally well tolerated and often included in moisturizing or repair-focused formulations.
| Reported effect | How often | Notes |
|---|---|---|
| Mild skin irritation | Rare | Occasional transient redness or stinging, typically at higher concentrations or on compromised skin. |
| Allergic contact dermatitis | Very rare | Isolated sensitization reports; uncommon given its endogenous amino acid nature. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.