Does giving paracetamol to lower raised temperature interfere with the body's natural defence response to infection?

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Practice question: All the nurses I know give paracetamol to lower a raised temperature even when the patient is not distressed. Some actually cause distress by removing blankets from a shivering patient with pyrexia. Surely both these actions are interfering with the body’s natural host defence response to infection?

Pyrexia is a common clinical finding in illness, often indicating infection. The body’s immune response triggers heat generating strategies to kill invading bacteria and viruses. Interventions that interfere with this response may be unhelpful, particularly if they actually cause distress to the patient.

Physiological response to infection
Protective role of pyrexia

• Increase antibody production;

• Enhance mobility and function of neutrophils and macrophages (kill bacteria);

• Increase production of cytokines (assist with immune response);

• Enhance T-lymphocyte activity (attack and destroy antigens);

• Reduce serum iron (necessary for bacterial growth);

• Inhibit some pathogens such as Streptococcus pneumoniae.  

The temperature regulating centre in the hypothalamus acts as an internal thermostat, regulating body temperature. The body’s thermoregulatory mechanisms strive to maintain core temperature at a level or set point of about 37°C.

In the presence of infection, pyrogens (fever producing proteins) are released and act upon the hypothalamus. The subsequent release of prostaglandins resets the hypothalamic thermostat to a higher level, triggering mechanisms to conserve heat, such as vasoconstriction, and generate heat, such as shivering, until the new set-point temperature is achieved (Waugh and Grant, 2006). This results in pyrexia (Royal College of Nursing, 2008).

Pyrexia has a protective role in infection, resulting from enhanced immune and cytokine functions. A rise in body temperature has been shown to:

Uncomplicated pyrexia is harmless and beneficial, as it is an important immunological defence mechanism (The Joanna Briggs Institute, 2001). Before antibiotics were available, syphilis was treated with fever which was induced with malaria, which was then subsequently treated with quinine usually successfully, though sometimes some patients did die of malaria (Vonderlehr, 1934).

Nurses’ knowledge of pyrexia and its management is poor; this frequently leads to inappropriate and ineffective management (Walsh et al, 2005). In intensive care, pyrexia may lead to unnecessary diagnostic tests, exposing patients to invasive procedures and inappropriate antibiotic use (Marik, 2000).

It has been argued that pyrexia should be treated with antipyretic drugs (Bruce and Grove, 1992). However, this may mask the signs of infection and make diagnosis and monitoring more difficult, so antipyretic drug therapy is now not recommended (Leach, 2009). In children, it should only be considered if the fever is causing them distress (National Institute for Health and Clinical Excellence, 2007).

Shivering is one of the body mechanisms to generate heat and increase body temperature. It is due to violent involuntary contraction of muscles, particularly in the skin. When shivering is associated with fever, it is often termed a rigor. Once the ‘set-point’ temperature is reached, shivering will stop. 

If patients start to shiver they should be kept covered in light clothing and a blanket to assist heat preservation (Brooker and Waugh, 2007). Removing clothing and bed linen is not helpful and can cause distress.

Pyrexia is associated with adverse effects. Oxygen consumption levels increase by 10% with each 1°C rise in temperature (Lenhardt et al, 1996). Pyrexia >40°C can lead to life threatening complications; specific interventions including physical cooling methods may be indicated.

Pyrexia can also be associated with acute illness. Assess and treat the patient (if necessary) following the airway, breathing, circulation, disability, environment (ABCDE) approach recommended by the Resuscitation Council UK (2006). Regular temperature measurements should be undertaken and expert help sought, if indicated, following emergency warning system protocols.

Half of pyrexias encountered are non-infection related, so patients who develop pyrexia should always be closely monitored.

Administering antipyretic drug therapy to patients with pyrexia and removing blankets from shivering patients are not recommended, as they can interfere with the body’s immune response to an infection and can be unhelpful.

AUTHOR Phil Jevon, PGCE, BSc, RN, is resuscitation officer/clinical skills lead, Manor Hospital, Walsall 

Brooker C, Waugh A (2007) Foundations of Nursing Practice: Fundamentals of Holistic Care. Elsevier: Edinburgh 

Bruce J, Grove S (1992) Fever: pathology and treatment. Critical Care Nurse; 12: 1, 40-49.

The Joanna Briggs Institute (2001) Management of the child with fever. Best Practice; 5, 5.

Lenhardt R et al (1996) Thermoregulation and hyperthermia. Acta Anaesthesiologica Scandinavica; Suppl; 40: 34-38.

Marik P(2000) Fever in the ICU. Chest; 117: 855-869.

NICE (2007) Feverish Illness in Children: Assessment and Initial Management in Children Younger than 5 Years of Age. London: RCOG Press.

Resuscitation Council UK (2006) Medical Emergencies and Resuscitation. London: RCUK.

Vonderlehr R (1934) Malaria treatment of parenchymatous syphilis of the central nervous system.Public Health Reports; Suppl 107; 7: 8, 1052.

Walsh A et al (2005) Fever management: paediatric nurses’ knowledge, attitudes and influencing factors. Journal of Advanced Nursing; 49: 5, 453-464.

Waugh A, Grant A (2006) Ross and Wilson’s Anatomy and Physiology in Health and Illness. London: Elsevier.