My 8 year old has a virus that is giving her an upset stomach. My wife had it a few days prior to my daughter. What OTC drug can I give to help her?

Gastroenteritis. "Stomach viruses" are, unfortunately, very common in summer. Aside from perhaps simethicone to reduce gas discomfort with diarrhea, no medicines are recommended for children with these symptoms. The best thing to do is encourage fluids, particularly with electrolytes, to help with hydration. Avoiding lactose-containing foods can help. If the symptoms persist over 48 hrs, she should see her doc.