In most people, the effect of the "once a day" will remain undiminished, even if you use the capsules for a long time. However, in certain circumstances, the effect may be temporarily reduced, for example in case of illness (with vomiting, diarrhoea) or when taking an antibiotic treatment. In this case we recommend temporarily stopping taking the capsules and trying again later. If it still does not work as it used to, you can choose an alternative, such as our lactase 20,000 tablets.