Final answer:
Jackie Lamington's mother should be instructed to apply the topical medication as prescribed without altering the frequency or quantity, and to monitor for efficacy and potential side effects.
Step-by-step explanation:
The appropriate guidance for Jackie Lamington's mother regarding the application of a topical medication to treat the infant's skin rash is to apply the recommended amount as prescribed. It's crucial to follow the prescribed dosage and not to overapply or underapply the medication. Although a newborn's skin may have a greasy material (vernix) and can appear thick, the medication is designed to penetrate and work effectively given the right application. Overuse can lead to excessive absorption and potential side effects, while underuse might result in an inadequate response to the treatment. The nurse should stress the importance of consistent and correct application, rather than frequency or quantity alterations. Additionally, close monitoring of the rash and any side effects in response to the medication should be advised.