A predominant part of the Swedish population uses toothpaste daily. Besides fluoride preventing caries, toothpastes usually have flavours added to make the user feel fresh and clean. Among potential allergens in toothpastes, flavours are the most common cause of oral or perioral lesions. Flavour concentrations vary between 0.3% and 2.0%, and usually several types of mint are used; however, the true composition of the added aroma is seldom known. l‐Carvone is a mint‐tasting flavour that can act as a potential allergen. Previous findings have shown that approximately 4% of a patch‐tested selected population in southern Sweden had a positive reaction to l‐carvone and half of them had oral inflammatory lesions, notably oral lichenoid lesions. Among patients with lichenoid lesions approximately 12% have a contact allergy to l‐carvone and several other contact allergies are more common in this patient group. The concentration of l‐carvone in toothpastes available for sale on the Swedish market was investigated. Sixty‐six different toothpastes were selected from local stores and pharmacies. l‐Carvone content was extracted from toothpastes using n‐heptane. The sample extracts were separated on a silica column using straight‐phase high‐performance liquid chromatography and a diode‐array detector. Three samples of each toothpaste were analysed, and the mean concentration and relative SD were calculated. Detectable levels of l‐carvone (0.00005–0.35%) were found in 63 of the toothpastes. l‐Carvone was found in half of the toothpastes (n = 32) at a concentration of ≥ 0.01%. A higher concentration (≥ 0.1%) was found in 18% (n = 12). Of the top six toothpastes with highest l‐carvone content (0.15–0.35%), one was intended for use by children. Two of the toothpastes were stated as having fruit flavour, but there were still detectable levels of l‐carvone (0.0003% and 0.00007%, respectively). l‐Carvone was below detectable levels in three of the toothpastes, where one was stated as being without flavour. l‐Carvone is present in virtually all toothpastes on the Swedish market. It is therefore likely that l‐carvone in toothpastes is important for the induction of sensitization to l‐carvone, as contact allergy to l‐carvone is over‐represented in patch‐tested individuals with oral lichenoid reactions. However, are the concentrations demonstrated relevant for causing reactions or aggravating already existing lesions?