Oxothiazolidine (procysteine, a 2-oxothiazolidine-4-carboxylic acid derivative) is a cysteine prodrug used in skincare as an antioxidant intended to support intracellular glutathione synthesis. It is studied for its potential to reduce oxidative stress and contribute to skin brightening or protective effects.
| Reported effect | How often | Notes |
|---|---|---|
| Mild skin irritation or redness | Uncommon | Transient, typically resolves after discontinuation or with lower concentrations. |
| Contact dermatitis or allergic sensitization | Rare | Reported in sensitive individuals; patch testing advised. |
| Stinging or burning on application | Uncommon | More likely on compromised or freshly exfoliated skin. |
| Systemic effects from topical use | Very rare | Topical dermatologic exposure rarely produces measurable systemic effects. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.