With medicine:

• Calcium salts reduce absorption of bisphosphonates, ciprofloxacin, fluorides, iron, levothyroxine, tetracycline and zinc
• Absorption of calcium salts is reduced by corticosteroids
• Increased risk of hypercalcemia when Calcium and Vitamin D3 given with thiazides and related diuretics

With food and others: No clinically significant food drug interaction have been reported.