Rigors (Shaking Chills): Causes, Associated Symptoms, and Urgency of Evaluation

Rigors are violent, involuntary shivering episodes accompanying a rapid fever spike. They reflect the hypothalamus resetting the thermal set-point upward.

Common Accompanying Symptoms

• High fever
• Headache, myalgia, fatigue
• Nausea, vomiting, diarrhea

Etiologies

• Infections: Bacteremia/sepsis, pneumonia, meningitis, UTI, malaria, TB.
• Non-infectious: Drug reactions, transfusion reactions, malignancy, heat stroke, thyroid storm.

Action

Rigors signal a significant underlying process. Urgent medical assessment (blood cultures, lactate, imaging, targeted workup) is required.