Final answer:
The nurse should report tinnitus as an adverse effect of gentamicin IV, as it can indicate ototoxicity, which may require changes to treatment.
Step-by-step explanation:
In caring for a client who is receiving gentamicin IV on an acute care unit, the nurse should report signs of tinnitus to the provider as an adverse effect of the medication. Gentamicin can cause ototoxicity, which may manifest as tinnitus or even hearing loss. Reporting this symptom is critical as it might require alteration of therapy or further investigation to prevent permanent damage.