After-dinner mints are popular not only because of the flavor, but because peppermint consumed after a meal can reduce gas and help with digestion. The cooling menthol in peppermint oil stimulates the stomach lining and eases stomach pain, so sucking peppermint candy may calm your upset stomach. If your symptoms of indigestion are related to gastroesophageal reflux disease, or GERD, peppermint products should not be used.