The characteristic feature of haemophilia is excessive bleeding, i.e. bleeding that takes longer to stop. In addition, in people with haemophilia, bleeding is easier and more frequent than in the rest of the population.
Depending on the severity of haemophilia, bleeding can occurred by an injury (severe or minor), a surgery, a dental operation, or even without an obvious cause (that is, the individual cannot determine the reason that caused the bleeding). In the latter case this is called a spontaneous bleeding. Spontaneous bleeding can occur in people with moderate and severe haemophilia.