Calcium carbonate antacids may cause constipation and hypercalcemia; which patients should use caution or avoid?

• A. Those with dehydration
• B. Those with low blood sugar
• C. Those with hypertension
• D. Those with hypercalcemia, kidney stones, or significant renal impairment.

Answer: (D)

Calcium-containing antacids can raise calcium levels in the body and slow intestinal movement, causing constipation. They are best avoided or used with extreme caution in people who already have problems with calcium balance or excretion. Specifically, if someone has hypercalcemia, they should not take calcium carbonate antacids because it would worsen their high calcium level. Likewise, those with kidney stones—especially calcium-containing stones—are at higher risk of stone formation with added calcium. And in significant renal impairment, the kidneys can’t clear the extra calcium effectively, increasing both hypercalcemia risk and stone formation.

Other conditions like dehydration, low blood sugar, or hypertension don’t pose the same direct risk related to calcium load, so they aren’t the primary concern for avoiding these antacids.