Get emergency medical help if you have signs of an allergic reaction to mirtazapine (hives, joint pain, fever, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.
Call your doctor at once if you have:
racing thoughts, decreased need for sleep, unusual risk-taking behavior, feelings of extreme happiness or sadness, being more talkative than usual;
blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
a light-headed feeling, like you might pass out;
severe rash, blisters, or swelling on the palms of your hands or the soles of your feet;
a seizure;
low white blood cell counts - fever, chills, sore throat, cough, sores in your mouth or nose, flu-like symptoms, trouble breathing; or
low sodium level - headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady.
Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.
Common mirtazapine side effects include:
drowsiness, dizziness;
increased appetite; or
weight gain.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Mirtazapine side effects (more detail)
