To: Denise Ferrell: Re: Peppermint Peppermint oil when used orally contains menthol and various terpenes. It can produce idiopathic atrial fibrillation, swelling of tongue, lips, and gingival mucosa, urticaria(rash, itching), and headache. Lets keep this stuff on the collar, and don't ingest it. It does smell nice, though. TWHale