I found this online: Contains saponins, digestion of which results in hydrolysis and production of toxic substances. Ingestion has emetic and purgative effects and is reported to cause laboured breathing, convulsions and coma. Not recently reported to have caused poisoning as its potential harm is well understood.
Prolonged handling can result in skin irritation. Wearing gloves, if possible, when working with ivy is recommended.
The Auckland Regional Council, see below, says that dust from Ivy can lead to sneezing and eye irritation. For that reason, many people say it should not be brought into the house.