Description eucalyptol is a natural organic compound which is a colorless liquid. it is a cyclic ether and a monoterpenoid. eucalyptol is an ingredient in many brands of mouthwash and cough suppressant. it controls airway mucus hypersecretion and asthma via anti-inflammatory cytokine inhibition. eucalyptol is an effective treatment for nonpurulent rhinosinusitis. eucalyptol reduces inflammation and pain when applied topically. it kills leukaemia cells in vitro.