Thiamine HCl is the water-soluble salt form of vitamin B1, used in topical formulations as a skin-conditioning agent and antioxidant support ingredient. Topical efficacy data are limited, and it is generally considered a supportive rather than a primary treatment active.
| Reported effect | How often | Notes |
|---|---|---|
Mild skin irritation or stinging | Rare | Occasional transient irritation reported at application site. |
Allergic contact dermatitis | Very rare | Isolated case reports of sensitization to topical thiamine. |
Contact urticaria | Very rare | Rarely documented; more associated with injectable forms. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.
Peer-reviewed papers on this ingredient, via PubMed.