Eugenol

What it is

Eugenol is the phenol responsible for the smell of cloves, and it is also present in cinnamon leaf, basil and bay oils. It is one of the eight components of the classic fragrance mix I patch-test panel, so it has been tracked in European contact-allergy surveillance for decades. It is used in cosmetics for spicy warm notes and, in dentistry, as a mild local anaesthetic.

What it does well

• Genuine antioxidant and antibacterial activity in the laboratory

  Eugenol is an effective radical scavenger and inhibits several bacteria in vitro. The concentrations required exceed normal cosmetic fragrance levels, so this should not be read as a skincare active.

  Moderate evidence

Worth knowing

• One of the more frequently positive components of fragrance mix I

  Eugenol is a moderate sensitiser and a recognised cause of allergic contact dermatitis, including occupational cases in dentistry and aromatherapy. It also cross-reacts with isoeugenol, a stronger allergen.

  Matters most toPeople with eczema, perioral dermatitis or a known fragrance allergy.

• Can irritate at higher concentrations

  Clove oil applied neat is irritant and can cause chemical burns on mucous membranes. In a finished face mask the level is a small fraction of a per cent.

  Matters most toPeople using undiluted clove oil at home.

Where the EU stands