laevolac is available as a clear, sweet-tasting liquid. The small volume of 15 mL of a single dose of laevolac is easier to take than bulk-forming or unpleasantly tasting laxatives.
Lactulose, the active ingredient in laevolac, is used as an energy source by bifidobacteria and lactic acid bacilli. As these bacteria grow, they increase the bulk of the stool. With the rising bacterial activity the acidity of the stool increases. This causes more water to be retained inside the colon.

In other words, laevolac acts by supporting the colonic flora to activate the natural function of the colon. Hence, laevolac is different from other osmotic laxatives because it activates our own beneficial gut bacteria to relief constipation. And because of this natural mode of action laevolac acts gently with a good tolerability, differentiating it from stimulant laxatives.