Quick answer
Monoterpene commonly found in citrus oils; Primarily used as a fragrance in cosmetics; Oxidizes when exposed to air; Can cause skin sensitization
Limonene
Updated
1-Methyl-4-Isopropenylcyclohexene; dipentene
Purpose
A volatile chemical compound often found in citrus oils. It’s used as a fragrance and solvent but can sensitize skin.
Rating
WORST
Category
Fragrance: Synthetic and Natural, Irritant, Plant Extracts
INCI Purpose
DEODORANT, PERFUMING, SOLVENT
Risks
Alternative Names
Hair Profile
Role
Phototoxic; degrades color and causes cuticle damage under UV light. Found in "natural" leave-in sprays used outdoors.
At a Glance
Monoterpene commonly found in citrus oils
Primarily used as a fragrance in cosmetics
Oxidizes when exposed to air
Can cause skin sensitization
Article
Limonene is a monoterpene and chemical constituent found in many plants, notably citrus fruits such as lemon (d-limonene is highly concentrated in the oil) and pine trees or species of the mint family (l-limonene). In cosmetics and skin care, limonene is primarily used as a fragrant ingredient and solvent.
Topically, limonene can cause sensitivity and is best avoided. Like most volatile fragrance components, limonene also has strong antioxidant benefits and has also been shown to calm skin; however, when exposed to air these highly volatile antioxidant compounds oxidize and become capable of sensitizing skin.
Also, because of its penetration-enhancing effects on skin, it’s particularly important to avoid products that contain limonene plus other skin sensitizers like denatured alcohol.
In the European Union, cosmetics and skin care ingredients with limonene in concentrations above 0.001% in leave-on products and 0.01% in rinse-off products must be declared on the ingredient list instead of just including limonene in the general designation of “fragrance”.
Limonene also has applications in the food industry.
See: Linalool
References