Poison Sumac. Poison sumac, Toxicodendron vernix, is related to the poison ivies and poison oaks, not to the other sumacs. It is relatively rare, compared to the other members of the family. The rash-causing agent, urushiol, is the same, and it causes the same rashes.
Most symptoms relate to movement of the face and hands, although some variants on this disorder have different symptoms. Almost always, tardive dyskinesia symptoms involve involuntary movements of some kind. In variants of tardive dyskinesia, a person may feel driven to move but may be able to control movement for a while. Usually, tardive dyskinesia symptoms include mouth and hand movements, although the limbs may move as well. Making faces, such as grimacing or puckering the lips, is common. One distinctive movement is the constant chewing associated with this disorder. The tongue may also protrude or move in unusual ways.
Medical Definition of Tardive dyskinesia. Tardive dyskinesia: A neurological syndrome characterized by repetitive, involuntary, purposeless movements caused by the long-term use of certain drugs called neuroleptics used for psychiatric, gastrointestinal, and neurological disorders.