If you use it, make sure you use the dose recommended on the package. Before you use any medicine for diarrhea, always check with your health care provider first. If you have been vomiting for more than a day or have had diarrhea for over 3 days, call your health care provider. You may need to have a physical exam to rule out more serious problems and to check for dehydration. You may also need to have lab tests to determine whether bacteria or protozoa are causing your illness.
Dehydration is a potentially serious complication of stomach flu.
It can occur if your body loses too much fluid because you keep vomiting or having diarrhea. In children and the elderly, dehydration can quickly become life threatening. Stomach flu rarely lasts longer than 1 to 3 days. However, it may be 1 to 2 weeks before your bowel habits return completely to normal. You develop symptoms that are not usually caused by stomach flu, such as blood in your vomit or bloody diarrhea.