Final answer:
The nurse should advise the client recovering from otitis externa to avoid cold water and wear soft plastic earplugs to protect the ear from water.
Step-by-step explanation:
The nurse should advise the client recovering from otitis externa to avoid cold water. Cold water exposure can worsen the symptoms and prolong the healing process. It is important to keep the affected ear dry and avoid any activities that involve submerging the ear in water.
Additionally, the nurse should instruct the client to wear soft plastic earplugs to protect the ear from water during activities such as swimming or showering.