Starburst candies are colorful and tasty, but they can be dangerous for dogs. The candy contains sugar and artificial flavors that can be harmful to dogs' health. If your dog eats a Starburst, you may notice he has an upset stomach, diarrhea, or vomiting. He may also have trouble breathing or develop a seizure. If you think your dog has eaten a Starburst, call your veterinarian immediately.