No grass snakes are not poisonous but it still really hurts if you do get bitten so I would be careful
Are Grass Snakes Poisonous?
No, Grass Snakes are not "poisonous", or venomous. Actually, there's no such thing as a "poisonous" snake at all, since a poison is something you either have to swallow or breathe in for it to harm you. We don't have Grass Snakes in the United States, by the way. That is a European species, related to Water Snakes.