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

Mirtazapine is an antidepressant that is often associated with significant weight gain as a side effect. This occurs because the medication can stimulate appetite, leading to increased caloric intake and consequently weight gain. Mirtazapine affects various neurotransmitters, including norepinephrine and serotonin, and this impact can influence hunger and satiety signals in the brain.

The other options typically do not align with the side effects seen in patients taking Mirtazapine. Weight loss would be contrary to the common effect of this medication. Diarrhea is not typically associated with Mirtazapine; in fact, constipation is more commonly noted. Increased anxiety is also not a usual side effect; while anxiety can sometimes occur in various contexts when starting or adjusting antidepressants, Mirtazapine is often used to help reduce anxiety symptoms. Thus, the most accurate representation of a common side effect of Mirtazapine is major weight gain.