You are the registrar on duty in the children’s emergency department. A registered children’s nurse asks you about an 18-month-old child who came in with his parents. He has been vomiting for the last 24 h and has today developed loose watery diarrhoea. His mother is concerned that his oral intake is poor and his nappies are not as wet as normal. The GP prescribed some oral rehydration solution yesterday, but the child is refusing to drink it. A neighbour told the mother that allowing the child to drink “flat” cola was a good way to prevent him from getting dehydrated. The nurse asks you if this is a safe and acceptable treatment to recommend for children. You have heard it mentioned by parents of children with gastroenteritis before but feel unsure whether any evidence supports it.

Structured clinical question

In children with viral gastroenteritis [subject] do “flat” fizzy drinks such as Coca-Cola [intervention] compared with oral rehydration solution [comparison] offer …