The primary side effect of a full moon in werewolf mythology is the transformation of an infected human into a werewolf. Early werewolf myths claimed that someone could become infected by sleeping beneath a full moon on a Friday, and later myths built on the idea of the moon influencing werewolf transformation. However, the full moon was originally only one of several possible reasons given for someone's transformation into a werewolf.
Ancient Greek myths held that humans could be transformed into werewolves by eating a mixture of wolf and human flesh, creating an irreversible transformation. Later myths held that such a transformation could come about from eating particular herbs or drinking water that was previously touched by a wolf. Other moon-specific myths claimed that individuals who were either cursed or conceived under the light of a full moon were infected by periodic transformation.
One reason for the popularity of the moon myth regarding werewolves is that police and emergency personnel often report that nights of a full moon are more dangerous than other nights because of an increase in crimes perpetuated by dangerous and crazy individuals. However, such stories remain only anecdotal as there has been no scientific link found between the appearance of a full moon and how dangerous an individual is.