Cherry pits are poisonous to humans, particularly if they are chewed or crushed. They contain amygdalin, a chemical that breaks down as cyanide in the body.
According to Right Diagnosis, swallowing cherry pits whole is unlikely to be problematic as the cyanide remains mostly contained within the cherry pit, and the body absorbs minimal quantities of the chemical. Symptoms of mild poisoning due to ingestion of crushed or chewed cherry pits include anxiety, headache, confusion, dizziness and vomiting. Right Diagnosis warns that more severe poisoning can cause breathing difficulties, elevated blood pressure and heart rate and kidney failure. Coma, convulsions and death can ensue. Treatment involves inducement of vomiting, stomach pumping and administration of various substances to absorb the poison.