Yes the snake plant is poisonous to humans and even animals if accidentally ingested so if you have pets or small kids that put things in their mouths then it's not recommended to have snake plants in your yard or house.
Snake Plants are wonderful plants to have in your garden or house but not if they poison your animal or kids.
All parts of the snake plant are toxic to humans and pets and if ingested the snake plant can cause nausea, vomiting, and diarrhea and possibly death if the animal or person is not treated soon after ingesting it.