Is it safe to take 2 tums (calcium carbonate) antacid chewables every day before bedtime?

Yes: But if you have persistent abdominal pain, you should consider getting an evaluation

Tums (calcium carbonate) : Yes. People take Tums (calcium carbonate) for heartburn, but also for other reasons, such as for its content of calcium. 2 Tums (calcium carbonate) per day shouldn't have any adverse effect, but your doctor should know you're taking it. Many antacids have a fair bit of aluminum in them, and your serum aluminum levels can actually rise with chronic use. But two a day should be safe.