PT - JOURNAL ARTICLE AU - Amro Maarouf AU - Sharon Jones TI - Lessons of the month: Over-the-counter antacids causing hypercalcaemia: The emergence of calcium-alkali syndrome AID - 10.7861/clinmed.2020-0208 DP - 2020 Jul 01 TA - Clinical Medicine PG - e129--e130 VI - 20 IP - 4 4099 - http://www.rcpjournals.org/content/20/4/e129.short 4100 - http://www.rcpjournals.org/content/20/4/e129.full SO - Clin Med2020 Jul 01; 20 AB - We present the case of a woman who was found to have severe hypercalcaemia, staghorn calculus formation and renal impairment from the long-standing ingestion of calcium carbonate antacids from a supermarket outlet. The dosage was reported to be approximately 1,800 mg of elemental calcium each day which would constitute only a marginal increase on the recommended intake for daily elemental calcium. Furthermore, she was concomitantly taking a prescribed anti-hypertensive medication that may have exacerbated the hypercalcaemia and subsequent renal calcification. While calcium-alkali syndrome is well documented, it can be overlooked by clinicians as the predominant cause of hypercalcaemia, especially if a thorough drug history is not actively sought. This is particularly important as calcium carbonate products are increasingly being purchased as over-the-counter remedies for dyspepsia management as well as osteoporosis prevention. Explicit product labelling regarding limiting duration usage, potential drug interactions and risk of calcification is therefore recommended.