Thioctic acid (alpha-lipoic acid) is a sulfur-containing antioxidant used in topical skincare for its free-radical scavenging and skin-conditioning properties. It is both water- and fat-soluble, allowing it to function across cellular environments.
| Reported effect | How often | Notes |
|---|---|---|
| Mild stinging or burning on application | Common | Transient sensation, especially at higher concentrations or on sensitive skin. |
| Skin redness or irritation | Uncommon | Localized erythema reported in some users; usually resolves on discontinuation. |
| Contact dermatitis | Rare | Allergic or irritant reactions documented in isolated cases. |
| Urticaria or hypersensitivity reaction | Very rare | Reported rarely; thioctic acid sensitization is uncommon but possible. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.
Peer-reviewed papers on this ingredient, via PubMed.