A potential adverse effect of mirtazapine when used for insomnia?

• A. Weight gain.
• B. Hyperactivity.
• C. Dehydration.
• D. Hypotension.

Answer: (A)

Weight gain is a well-known adverse effect of mirtazapine, especially when used for insomnia. The drug strongly blocks histamine H1 receptors, which contributes to sedation but also tends to increase appetite and caloric intake in many patients. Over time this can lead to noticeable weight gain, a common concern with nighttime mirtazapine treatment.

Other options don’t fit as well. Hyperactivity isn’t typical because mirtazapine has sedating effects. Dehydration isn’t a primary or common consequence of its use. Hypotension can occur but is less characteristic than weight gain, and it’s generally not the standout adverse effect seen with insomnia-focused dosing.