Can stress cause geographic tongue? i developed this after a very long stressful period and it seems to be better with stress reduction.

While the cause of: Geographic tongue is unknown, there may be a genetic link or it may be an autoimmune response. Stress often affects our bodies both in proven and unproven ways. It can often be a factor without a direct cause effect relationship and therefore may well play a role in your particular case.

The cause is unknown: The cause is unknown as is the role of stress in causing it. I am glad to hear that your stress reduction is seeming to help, because we typically are unable to do anything about it.