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ALPHA-TERPINENE.

Avoid CAS 99-86-5 / PERFUMING

Alpha-Terpinene is a naturally occurring terpene known for its antioxidant and antimicrobial actions, alongside potential roles in skin barrier support and pH balance. However, its high propensity for rapid autoxidation into potent allergens significantly impacts its safety profile for topical use.

Antioxidant Antimicrobial Anti-inflammatory Fragrance

Science

Alpha-Terpinene acts as an antioxidant by readily undergoing autoxidation, thus preventing the degradation of other compounds in a formulation. It also exhibits antimicrobial properties, can reduce inflammation and redness by promoting beneficial skin bacteria, and contributes to balancing skin pH and strengthening the skin's barrier function.


Research

Low confidence
Effective range N/A
Optimal

N/A


Transparency

Not commonly dusted

The Formula

Solubility
Oil
Optimal pH N/A
0 7 14

Stability

Alpha-Terpinene undergoes rapid autoxidation upon air exposure, forming allylic epoxides and other oxidation products that are strong skin allergens and sensitizers.

Conflicts

  • Air/Oxygen

Safety

CIR Status
Not reviewed
Sensitization risk High

While Alpha-Terpinene is Generally Recognized as Safe (GRAS) by the FDA for use as a flavoring agent in food, its suitability for topical applications in cosmetics is highly concerning. In Europe, it is classified as a regulated allergen. Its rapid autoxidation upon air exposure creates potent skin sensitizers, with the oxidized form demonstrating nearly nine times higher sensitization potency compared to pure Alpha-Terpinene, leading to a significant risk of allergic skin reactions and irritation. The EWG notes restrictions for its use, particularly highlighting respiratory concerns in inhalable product forms.


Your Skin

No Normal
No Dry
No Oily
No Sensitive
Irritancy High
Comedogenicity Unknown

Our Assessment

Avoid

Despite exhibiting antioxidant and antimicrobial properties, Alpha-Terpinene's rapid autoxidation into potent skin sensitizers, with an almost 9-fold increase in sensitization potential when oxidized, renders it a high-risk ingredient for topical applications, warranting avoidance.


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