Abstract: A magnesium citrate oral solution comprising citric acid in an amount greater than 10% weight/volume; magnesium hydroxide in an amount ranging from about 1.5-5% weight/volume; and water. Most preferably, the citric acid is present in an amount of about 10.9% weight/volume. Another embodiment of the present invention is a method of treating constipation in a patient in need thereof. The method of this embodiment comprises administering an effective amount of an oral composition that comprises citric acid in an amount greater than 10% weight/volume. Preferably, the composition of this embodiment comprises citric acid in an amount of 10.9% weight/volume.