Why do my hands get cold when i am anxious?

Adrenaline: When people get anxious there is a release of adrenaline which tends to constrict the circulation in the limbs. Presumably, its role in the "fight or flight" emergency reactions of the body is to diminish blood loss if you were to get slashed & to make sure that plenty of blood is going to the major organs.

Circulation changes: Anxiety has many physiological consequences including increased heart rate, increased respiratory rate, dry mouth, increased frequency of urination and changes in peripheral circulation. Your hands might get cold as a result of reduction in blood flow to your hands. Numbness and tingling can also result. Some of these peripheral consequences can be mitigated by the use of a beta-blocker.