Calcium carbonate × Lithium

Calcium carbonate as an antacid mildly reduces lithium intestinal absorption, but no clinically significant drop in blood concentration has been documented.

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

No dose adjustment needed. Check lithium levels on the usual schedule (every 3 months on stable dose). With significant clinical changes (return of manic or depressive symptoms), check off-schedule.