Diarrhea isn t fun, especially for children. (in that case, diarrhea isn t fun for mom and dad, either.) diarrhea and vomiting can drain your child s body of the water and electrolytes he or she needs to stay healthy. when illness saps a child s fluid levels, it s important to contact your healthcare provider and work together to get those fluids? and electrolytes? replenished right away.