What it does
- Provides broad antioxidant protection in both water and oil environments.
- Supports a smoother, more refined-looking skin surface.
- Used in anti-ageing and radiance formulas.
How it works
Alpha lipoic acid is unusual in being soluble in both water and oil, so it is widely documented to act as an antioxidant across skin compartments. It can be potent but is also unstable and has a characteristic sulphur odour, which shapes how it is formulated.
Use level
- Typical use level
- typically 1–5%
Commonly used at 1–5%. Higher levels can tingle in sensitive skin. Start lower to assess tolerance.
Formulation considerations
- Amphiphilic; can be incorporated into the water or oil phase.
- Prone to oxidation and has a sulphur odour; stabilise and consider fragrance masking.
- Best in mildly acidic systems; protect from light.
What it pairs with & what to avoid
Pairs well with
- Other antioxidants (vitamin C, E)
- Hydrators and soothing actives
Use with care / avoid
- High levels in reactive skin (tingling)
- Prolonged light/air exposure without stabilisation
Regulatory status
Thioctic acid (alpha lipoic acid) is listed in the EU CosIng database and is a well-established antioxidant ingredient.
Common questions
What does alpha lipoic acid do for skin?
It is a dual water- and oil-soluble antioxidant that protects skin and supports a smoother, more refined surface.
What percentage of alpha lipoic acid is used?
Typically 1–5%; start lower in sensitive skin.
Why does alpha lipoic acid smell?
It contains sulphur, giving a characteristic odour that formulators manage with fragrance and stabilisation.