Chilblains are what is classified as a non-freezing cold injury and frostbite is a freezing cold injury.
Chilblains are an abnormal reaction of the small blood vessels to nonfreezing cold that typically causes an itching rash and pain. With treatment and with the avoidance of cold they recover fully.
Frostbite is a freezing of a body part and the tissue that is frozen will die (necrosis) and is much more serious than chilblains as complications can develop. Usually, the necrotic tissue needs to be removed surgically.
