Nexium (esomeprazole ) is a medication that works on decreasing the amount of stomach acid production. It is considered a safe drug for the use in infants and children, when indicated. The main concern is with the long-term use of the drug; since it decreases the stomach acidity, this increases the likelihood of overgrowth of germs such as fungi.
May I know why is your child on Nexium and the duration of treatment (when was it started? For how long was it prescribed?).