phudina :

Precautions:

No internal use of peppermint oil with people that have gall stone disease, occlusion of bile ducts, gall bladder and liver damage. For external use do not apply peppermint oil directly onto mucous membranes or broken skin and never in the area around the eyes.

For infants and toddlers up to 2 years old, menthol can cause spasms or respiratory arrest, therefore peppermint oil may not be used in this age group. As a matter of precaution it is not recommended for children up to 4 years old.

There are no studies on the safety of using peppermint during pregnancy or lactation.

Toxicity studies:

When used externally there may be occasionally skin irritations and eczema, and internally stomach aches in people with sensitive stomachs. In the case of inhalation-sensitive patients may be show adverse respiratory reactions.