Peppermint is safe for dogs
Peppermint is not toxic to dogs, but it does contain oils which can cause vomiting and diarrhea with large ingestions. Avoid giving peppermint flavored candy to your dog because the sugar content is unhealthy for dogs, and sugar free varieties may contain xylitol which is toxic. Do not use peppermint essential oils on your dog. They are toxic whether applied on the skin or given orally.