Final answer:
A spacer with a fluticasone inhaler primarily reduces the risk of oral thrush by minimizing medication contact with the oral mucosa and preventing its deposition in the mouth.
Step-by-step explanation:
When teaching a child about using a spacer with a fluticasone inhaler, the nurse should highlight its role in reducing the risk of oral thrush. A spacer helps to deliver medication directly to the lungs and decreases the medication's contact with the oral mucosa, which reduces the likelihood of fungal infections such as oral thrush. Spacers also aid in preventing the deposition of medication on the back of the throat and on the oral surfaces, thereby diminishing the chances of local side effects.