Repeated exposure may produce chronic respiratory distress, particularly in susceptible individuals. An existing dermatitis may also be worsened by repeated exposure to the liquid. Diborane has not been shown to have carcinogenic or reproductive or developmental effects in humans. Diborane reacts with halogenated hydrocarbons, and fire extinguishing agents such as Halon or carbon tetrachloride are therefore not recommended. Carbon dioxide extinguishers should be used to fight diborane fires.
Fires involving diborane sometimes release toxic gases such as boron oxide smoke.
Diborane is a strong reducing agent that produces hydrogen upon heating or upon reaction with water. Contact with aluminum, lithium, and other active metals forms metal hydrides, which may ignite spontaneously. Diborane is incompatible with oxidizing agents, halogens, and halogenated compounds. Diborane will attack some forms of plastics, rubber, and coatings. In particular, diborane should be used only in a fume hood free of ignition sources and should be stored in a cold, dry, well-ventilated area separated from incompatible substances and isolated from sources of sparks and open flames.