Toxicology
The toxicity studies of the plant have received controversial results. Some authors reported that the plant may induce hepatic diseases (liver disease), while others found that it protects against liver damage that is caused by heavy metals. In addition to that, the toxicities of the plant seem to vary from one cultivar to another and are dose dependent. This is probably attributed from the content level of pulegone.
With the limitation that the concentration of pulegone should not exceed 1%, it has been concluded that Mentha Piperita (Peppermint) Oil, Mentha Piperita (Peppermint) Extract, Mentha Piperita (Peppermint) Leaves, Mentha Piperita (Peppermint) Water are safe as used in cosmetic formulations.
Peppermint also contains terpenoids and flavonoids such as eriocitrin, hesperidin and kaempferol 7-O-rutinoside.
Read more about this topic: Peppermint