Milk-alkali syndrome is an acquired condition in which there are high levels of calcium (hypercalcemia) and a shift in the body's acid/base balance towards alkaline (metabolic alkalosis).

Milk-alkali syndrome is caused by excessive consumption of milk (which is high in calcium) and certain antacids, especially calcium carbonate or sodium bicarbonate (baking soda), over a long period of time.

Calcium deposits in the kidneys and in other tissues can occur in milk-alkali syndrome. Consumption of excessive amounts of vitamin D, which is usually added to milk bought at the supermarket, can worsen this condition.

In the past, milk-alkali syndrome was often a side effect of treating peptic ulcer disease with antacids containing calcium. It is rarely seen today, because newer, better medications are available for treating ulcers. A more common scenario today is when someone takes too much calcium carbonate in an attempt to prevent osteoporosis. This syndrome has been reported in persons who take as little as 2 grams of calcium per day.