Terpin hydrate is a cough suppressant and expectorant medication. It works by thinning the mucus in the airways, making it easier to cough up and clear. It is commonly used to relieve chest congestion and coughing associated with colds, flu, and other respiratory conditions. Terpin hydrate is available in liquid and tablet form and can be taken orally. It is generally considered safe when taken as directed, but may cause drowsiness or dizziness in some people. It should be avoided by people with certain medical conditions or taking certain medications, and should not be used for long periods of time without consulting a doctor.