Final answer:
The adverse effects of varenicline [Chantix] include sleep disturbances, mood changes, and nausea.
Step-by-step explanation:
The adverse effects that a patient taking varenicline [Chantix] should observe for include Sleep disturbances, mood changes, and nausea. These side effects are commonly experienced by patients when starting this medication. It is important for the nurse to educate the patient about these potential effects so they can effectively monitor and manage them.