Yes. Alocasia is a member of the Araceae or "Arum" family that are all are poisonous. They produce an irritant called calcium oxalate that can cause excruciating pain in the eyes, mouth, throat and stomach if ingested.  All parts of the plant including seeds, roots, leaves and flowers are toxic to humans so great care needs to be taken when handling Alocasia plants at home or in gardens with children or pets.