This poofy-flowered bush (Hydrangea macrophylla) is a popular yard ornament that can grow up to 15 feet tall with rose, deep blue or greenish-white flowers that grow in huge clusters and look as edible as cotton candy or a big bun to an imaginative mind. But those blooms will give you a belly ache that sets in sometimes hours after eaten. Typically, patients also experience itchy skin, vomiting, weakness and sweating. Some reports indicate that patients can even experience coma, convulsions and a breakdown in the body's blood circulation. Luckily, there is an antidote for hydrangea poisoning, and doctors might also give you drugs to address to ease your symptoms.