What is rigor (rigor mortis)?

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Last updated: April 21, 2025View editorial policy

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From the Research

A rigor is a sudden episode of shivering accompanied by a feeling of being cold and a rapid rise in body temperature, typically associated with fever or infection. Rigors occur when your body is trying to raise its core temperature quickly, causing muscles to contract and relax rapidly (shivering) to generate heat. These episodes are often intense and uncontrollable, lasting anywhere from a few minutes to an hour. Rigors commonly indicate the presence of a significant infection, particularly bacterial infections like pneumonia, urinary tract infections, or bloodstream infections. They may also occur with malaria, after certain medical procedures, or as a reaction to some medications. If you experience rigors, it's essential to measure your temperature, stay hydrated, and use appropriate fever-reducing medications like acetaminophen (325-650mg every 4-6 hours) or ibuprofen (400-600mg every 6-8 hours) if fever is present, as suggested by general medical knowledge and not specifically mentioned in the provided studies 1, 2, 3, 4, 5. Some key points to consider when dealing with rigors include:

  • The importance of staying hydrated to help the body recover from the infection or condition causing the rigor
  • The use of fever-reducing medications to help manage symptoms and make the patient more comfortable
  • The need for prompt medical attention if rigors are severe, persistent, or accompanied by other concerning symptoms, as they may signal a serious underlying condition requiring specific treatment. It's also worth noting that while the provided studies do not directly address the topic of rigors, they do discuss related topics such as muscle cramps and contractures 1, 3, myoclonus and movement disorders 4, and the use of benzodiazepines in various medical contexts 2, 5. However, these studies do not provide specific guidance on the management of rigors, and therefore the recommendations provided are based on general medical knowledge and principles of patient care.

References

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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