Constipation after taking probiotics may be due to “Hirschsprung’s demise reaction”, i.e., the release of endotoxin when harmful bacteria in the intestinal tract die, resulting in intestinal reactions. Probiotics are widely recognized to help regulate the balance of intestinal flora, promote the proliferation of beneficial bacteria in the intestines, compete with harmful bacteria for nutrients and living space in the intestines, and inhibit the growth of harmful bacteria. Harmful bacteria release endotoxins when they die, which may lead to an increased intestinal response, a phenomenon known as the “Hirschsprung’s reaction”. The Hirschsprung’s reaction is usually not severe and the intake of probiotics can be reduced and then gradually increased once the symptoms have subsided. If symptoms do not improve or continue to worsen, it is important to seek medical attention to check for other conditions.