Teeth chattering is the experience of a compulsive and often uncontrollably rapid slight opening and closing of a person's mouth. The effect is similar to that of when a person is cold or afraid, though it should be noted that in this context (whereby the effect is a result of psychoactive compounds), teeth chattering occurs independently of such external stimuli.
Teeth chattering is often accompanied by other coinciding effects such as teeth grinding and vibrating vision. It is most commonly induced under the influence of heavy dosages of serotonergic compounds, such as MDMA and DXM. However, it can also occur under the influence of certain stimulating psychedelics such as 2C-E, DOC, and AMT.