This compound stimulates the nervous system producing restlessness, excitement, tremors leading to seizures and coma. Other signs which may be seen include vomiting, diarrhea, rapid breathing, increased drinking, incontinence (loss of bladder control), and sudden death.

Signs usually reach their peak around four hours after poisoning but can last for up to eighteen hours. Death from heart complications has been reported as much as three days after initial effects are observed.

Treatment is nonspecific. Animals detected early in the course of the poisoning can be made to vomit. Seizures should be controlled with tranquilizers or anesthetics and stomach washes may be performed.

Sweet chocolate can be fatal at doses of 100g/kg while unsweetened chocolate has caused death at 20g/kg