Discontinue use if a rash develops. Menthol, the active ingredient that gives peppermint its kick, relieves nasal, sinus and chest congestion. Peppermint is, in fact, one of the few Food and Food Drug Administration-approved remedies for the common cold. So next you're sick, try a cup of peppermint tea. But you shouldn' t give peppermint tea to infants or very young children, counsels Varro E. Tyler, Ph. D., professor of pharmacognosy at Purdue University School of Pharmacy in West Lafayette, Indiana.
Peppermint oil is a more serious matter.
It's highly concentrated and should be used only in the small amounts recommended here. Pure menthol is poisonous and should never be taken internally.