* Breathing Magnesium Oxide can irritate the eyes and nose. * Exposure to Magnesium Oxide can cause “ metal fume fever .” This is a flu-like illness with symptoms of metallic taste in the mouth, headache, fever and chills, aches, chest tightness and cough.DENTIFICATION Magnesium Oxide is a white powder. When finely divided Magnesium Oxide is dispersed in air it is called Magnesium Oxide fume. It is used in the metals refining industry, in electrical insulating material, and as a supplement in animal feed.