The context of transient loss of consciousness (T-LOC) is shown. Two decision nodes separating T-LOC from other conditions are whether or not consciousness appeared lost or not, and whether the four features defining the presentation of T-LOC were present. Whereas ‘coma’ is usually reserved for long-lasting forms, there is no common name for disorders with a duration of unconsciousness intermediate between T-LOC and coma. Examples are metabolic derangements such as hypoglycaemia and various intoxications.