Remeron serious side effect. Call your doctor at once if you have a serious side effect such as:

  • agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination
  • very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors
  • feeling like you might pass out
  • fever, chills, body aches, flu symptoms
  • white patches or sores inside your mouth or on your lips
  • headache, trouble concentrating, memory problems, weakness, or feeling unsteady