Our Son Is 31 Years Old. He Is Having Hallucinations

Our son is 31 years old. He is having hallucinations and feels everyone is out to get him. He has delusions of being spied on by drones or watched by "law enforcement" in unmarked vehicles. We cannot reason with him. It makes him angry that we don't believe him. He has never had a history of this kind of activity before, but it is getting worse. It has been 2 months now and we know he needs help. Any suggestions?