Is stomach flu serious?

Stomach flu is usually not serious but can be more dangerous if you are unable to replenish the fluids and electrolytes that get depleted through vomiting and diarrhea. Stomach flu is a very serious condition in developing countries where contaminated food and water are more common. For most healthy children and adults in the United States, there are few complications from stomach flu. But the stomach flu can be more serious for those with weakened immune systems, infants, young children, and the elderly, who are more susceptible to dehydration.