Magnesium (Mg2+) is the second intracellular cation after potassium and is an important cofactor in cellular enzymatic reactions. Its homeostasis is essential for many cells including those of the nervous system, cardiomyocytes and smooth or striated muscle cells. The balance of serum Mg2+ depends mainly on its intestinal absorption and its excretion by the renal distal convoluted tubule. While many etiologies including genetic diseases have been described as sources of imbalance in serum Mg2+, the occurrence of hypomagnesaemia during proton pump inhibitors (PPIs) treatment is rarely reported. The pathogenesis is poorly understood, and might be due to a decrease in intestinal absorption of Mg2+ during IPPs treatment.