Ammonia is a frequently used industrial agent. Ammonia is highly soluble in water and has toxic and corrosive actions caused by its alkalinity. It is easily absorbed through mucous membranes. Ammonia affects the upper airways more than the peripheral airways. Following exposure to ammonia, the clinical symptoms appear instantly and may consist of nasal discharge, lacrimation, pain in the upper airways, dyspnoea, bronchospasm, bronchial oedema, glottic oedema, increased mucus production, haemoptysis and cyanosis. Ingestion of ammonia water induces caustic lesions in the oropharynx, oesophagus and stomach. Liquid ammonia is corrosive. Evaporation of liquid ammonia from the eye or skin may cause cold burns.