Final answer:
Patients beginning varenicline [Chantix] should watch for adverse effects such as sleep disturbances, mood changes, and nausea, and discuss any issues with their healthcare provider.
Step-by-step explanation:
The adverse effects that a patient starting to take varenicline [Chantix] should observe for include sleep disturbances, mood changes, and nausea. These side effects are commonly reported among patients who are prescribed this medication for smoking cessation.
It is important for patients to be aware of these potential adverse effects and to communicate any concerns with their healthcare provider to ensure proper management and care.