Nitrous produces an immediate loss of motor control. Stay seated if you are going to inhale nitrous. There have been many injuries and a few deaths from people who have fallen down after inhaling nitrous. Brain damage and suffocation can result from inhaling pure nitrous for an extended period of time. Nitrous can be extremely cold when it comes out of the tank.
Cold gas can burn the skin as well as the lips and throat.
Dispensing the gas into a balloon and allowing it to warm up before inhaling it can reduce this risk. High pressure levels in the tank can shoot the gas out at a dangerously fast speed and damage the lungs. Again, it is safer to inhale from a balloon than from a tank. Nitrous can be psychologically addictive. While rare, many people have become addicted to nitrous and other dissociatives.