A citrus flavouring in toothpaste and mouthwash. Adds taste; no oral-health effect has been shown.
Lemon peel oil is pressed from lemon rind and used for flavour and scent. Its main components (limonene and citral) are common fragrance allergens, which is why EU labels must name them above set levels.
There is no clinical evidence that lemon oil in oral-care products benefits teeth or gums. It is a flavouring.