Tums Does Not Contain Magnesium
Tums contains calcium carbonate, not magnesium. The active ingredient in standard Tums formulations is calcium carbonate at 40% elemental calcium, with various strengths ranging from 500 mg to 1,500 mg of calcium carbonate per tablet 1.
Active Ingredient Composition
- Tums EX (extra strength) contains 750 mg calcium carbonate, providing 300 mg elemental calcium per tablet 1
- Tums Ultra contains 1,000 mg calcium carbonate, providing 400 mg elemental calcium per tablet 1
- Tums 500 contains calcium carbonate formulated to deliver 500 mg elemental calcium 1
Distinction from Magnesium-Containing Products
While Tums is purely calcium-based, other antacid products do contain magnesium compounds 2, 3:
- Aluminum/magnesium hydroxide combinations (such as Mylanta) contain magnesium hydroxide as an active ingredient 4
- Calcium/magnesium carbonate combinations (such as Rennie) contain both calcium carbonate and magnesium carbonate 5
- MagneBind products contain magnesium carbonate (57-85 mg) combined with calcium acetate, but these are phosphate binders rather than standard antacids 1
Clinical Implications
The absence of magnesium in Tums has important clinical consequences:
- Constipation risk: Calcium carbonate alone tends to cause constipation, unlike magnesium-containing antacids which cause diarrhea 6
- Acid rebound: Calcium carbonate can induce gastric acid rebound, where gastric pH may remain at or below baseline values after the initial neutralizing effect wears off 4
- Phosphate binding: Calcium carbonate (including Tums) can be used as a phosphate binder in chronic kidney disease, whereas magnesium-containing products should be avoided in renal insufficiency due to hypermagnesemia risk 1