A medicinal composition useful for the treatment of head and neck cancer premalignant lesions. The composition includes a curcuminoid mixture and an essential oil of turmeric. The curcuminoid mixture consists of curcumin, demethoxycurcumin and bisdemethoxycurcumin. The essential oil of turmeric includes about 45% ar-turmerone. The weight ratio of curcuminoid mixture to essential oil of turmeric ranges from about 1 : 3 to about 99 : 1. Methods of preparation of the composition is provide. Methods of treatment of head and neck cancer premalignant lesions by oral administration is provided.