Which of the following is a common side effect of bupropion?

Bupropion is known for its stimulating properties and is often prescribed as an antidepressant and for smoking cessation. A common side effect associated with the use of bupropion is dry mouth, or xerostomia. This occurs due to bupropion's effect on neurotransmitters in the brain, particularly its influence on dopamine and norepinephrine, which can subsequently impact salivary gland function and result in decreased saliva production. Patients may experience dryness in their mouth, making it uncomfortable and affecting their ability to eat or speak properly.

The other options, while they may be side effects of other medications or conditions, are not typically associated with bupropion. For instance, increased appetite and weight gain are more commonly linked to other antidepressants, particularly those that influence serotonin levels, while fatigue can also be a side effect of various medications but is not a hallmark of bupropion use. Thus, dry mouth stands out as a prevalent and characteristic side effect of bupropion.