Spearmint and spearmint oil are likely safe when eaten in amount commonly found in food. Spearmint is possibly safe when taken by mouth in medicinal amounts or when applied to the skin.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Spearmint is possibly safe when used in excessive amounts during pregnancy. Excessive use of spearmint tea might cause damage to the uterus. Avoid using in large amounts of spearmint during pregnancy.
There is not enough reliable information about the safety of taking spearmint if you are breast-feeding. Stay on the safe side and avoid using in amounts greater than those found in food.
Kidney disorders: Spearmint tea might increase kidney damage. Higher amounts of spearmint tea seem to have greater effects. In theory, using large amounts of spearmint tea might make kidney disorders worse.
Liver disease: Spearmint tea might increase liver damage. Higher amounts of spearmint tea seem to have greater effects. In theory, using large amounts of spearmint tea might make worsen liver disease.