Stop taking Desyrel and consult your doctor if following side effects appear. Blurred or tunnel vision, Eye pain or swelling, Seeing halos around lights, Headache with chest pain, severe dizziness, fainting, palpitations, Chest pain or pressure, Tight feeling in neck or jaw, sweating, pain in the arm, Serotonin syndrome: agitation, hallucination, fever, tachycardia, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting, Hyponatremia: headache, confusion, slurred speech, severe weakness, loss of coordination, fainting, Severe nervous reaction: rigid muscles, high fever, tremors, sweating, confusion, faintness, fast or uneven heartbeat, Dry mouth, Altered sense of taste, Constipation