Some of the most common side effects of mirtazapine (Remeron®) include dry mouth, an increased appetite, and drowsiness. Rare side effects have also been reported in less than 1 percent of people taking the drug. These include migraine headaches, seizures, and sexual side effects. If you develop serious side effects of mirtazapine, such as suicidal thoughts, hallucinations, or any signs of an allergic reaction, report them immediately to your healthcare provider.
(Click Side Effects of Mirtazapine for a more complete list of the common, rare, and serious side effects seen with the drug.)