Covonia Chesty Cough Mixture Mentholated contains liquorice and squill which belong to a group of medicines known as expectorants. They help remove phlegm in people with productive (chesty) coughs. Menthol helps relieve congestion associated with chesty coughs and bronchitis. Levomenthol. Squill Tincture. Liquorice Liquid Extract. Effective relief of troublesome chesty coughs. Non drowsy.chesty coughs. Expectorant. An oral solution for the symptomatic relief of productive (chesty) coughs and sore throats.