Are there any known drug interactions associated with the use of Covonia Mentholated Cough Mixture? ## This product contains: Menthol 4.0mg, Squill Tincture 0.6ml and Liquorice Liquid Extract 0.125ml. Therefore, it is an herbal remedy, not a medication and the side effects and interactions have not been studied. The only thing I can really tell you is that since it contains Licorice Extract, it should not be used by people who have high blood pressure, as this can cause it to go higher.