If you need a reasonable accomodation
or say you needed some time off if you were going to change the Lithium
or have another medication added (which might be an idea, Lamictal is one that worked for me) you would have to tell your supervisor in confidence at that time but they legally could not repeat it. As for your co-workers, it depends on the particular people. I certainly wouldn't make a group announcement. Tell the people you trust. And who knows some could have disabilities as well.