A small amount of chocolate, like the chips in a cookie, is normally not a problem. A larger amount, several ounces, can cause illness and death. The active ingredients in chocolate are theobromine and caffeine, so it makes sense that the signs of chocolate toxicity include hyperactivity, tremors, panting, and twitching. Very bad cases can lead to seizures, racing heartbeat (called tachycardia), abdominal pain, and death. Other signs include vomiting, diarrhea and decreased appetite- think of a small child who’s eaten too much candy.