Babies should not eat chocolate due to its high levels of caffeine. Caffeine is a natural stimulant found in the cacao that is used to make the chocolate.
It is best to avoid giving a baby or young child chocolate if possible, according to the parenting website What to Expect. In addition to the high levels of caffeine, chocolate also contains high levels of sugar. Both of these can cause excessive stimulation of babies and small children. According to About.com, another reason to avoid chocolate is its potential for causing an allergic reaction. Allergies from the chocolate itself are not common, but there is a good chance of a reaction occurring from exposure to nuts, dairy or soy.