Management of Fever
Antipyretic medications should not be routinely administered solely to reduce body temperature in febrile patients, as fever represents a protective physiological response and temperature suppression does not improve mortality or clinical outcomes. 1, 2, 3
Temperature Measurement
Use central temperature monitoring (pulmonary artery catheter thermistors, bladder catheters, or esophageal balloon thermistors) when these devices are already in place or when accurate measurements are critical to diagnosis and management. 1, 2, 3
For patients without central monitoring devices, measure temperature using oral or rectal thermometers rather than unreliable methods such as axillary, tympanic membrane, temporal artery, or chemical dot thermometers. 1, 2, 3
Diagnostic Workup
Perform a chest radiograph for all patients with new fever, as pneumonia is the most common infectious cause. 1, 2, 4
Obtain blood cultures immediately before antibiotic administration, ideally within 30-90 minutes of symptom onset, particularly when fever occurs with elevated neutrophils suggesting bacteremia. 2, 4
Complete blood count with differential, comprehensive metabolic panel, lactate level, and urinalysis with urine culture should be obtained to identify potential sources. 4
For patients who have recently undergone thoracic, abdominal, or pelvic surgery, perform CT imaging in collaboration with the surgical service if fever persists without identified etiology after initial workup. 1, 2
For patients with fever and abdominal symptoms, abnormal liver function tests, or recent abdominal surgery, perform formal bedside diagnostic ultrasound of the abdomen. 1
Do not routinely perform abdominal ultrasound in patients with fever who lack abdominal signs, symptoms, liver function abnormalities, or recent abdominal surgery. 1
Antipyretic Therapy: When to Treat
Reserve antipyretic medications for symptomatic relief and patient comfort, not for temperature reduction itself. 1, 2, 3
The primary goal should be improving overall comfort rather than normalizing body temperature, as fever itself does not worsen illness course or cause long-term neurologic complications. 5
For patients who value comfort through temperature reduction, use antipyretic medications rather than non-pharmacological cooling methods. 1, 3
Physical cooling methods such as fanning, cold bathing, and tepid sponging cause discomfort and are not recommended. 3
Antipyretic Drug Selection
Acetaminophen (paracetamol) 1000 mg orally every 4-6 hours (maximum 4 g/day) is the preferred first-line antipyretic for adults. 2, 6, 5
Reduce acetaminophen dose in patients with hepatic insufficiency or history of alcohol abuse. 2
Acetaminophen is contraindicated in acute liver failure. 2
The combination of paracetamol 500 mg/ibuprofen 150 mg may be more effective than single-agent therapy, particularly in patients with bacterial fever at one hour post-administration. 6
Ibuprofen 600 mg can be used as an alternative, though acetaminophen remains preferred due to its safety profile. 6, 5
NSAIDs including ibuprofen can be added to acetaminophen for enhanced prophylaxis against recurrent rigors. 4
Special Considerations for Underlying Conditions
Cardiovascular Disease
NSAIDs increase the risk of cardiovascular thrombotic events including myocardial infarction and stroke, which can be fatal. 7
This risk increases with higher doses and longer duration of NSAID use. 7
Avoid NSAIDs in patients with recent heart attack unless specifically directed by their healthcare provider, as they may increase the risk of another cardiac event. 7
Do not use NSAIDs immediately before or after coronary artery bypass graft (CABG) surgery. 7
NSAIDs can cause new or worsening hypertension and heart failure; monitor for shortness of breath, unexplained weight gain, or edema. 7
Renal Disease
NSAIDs can cause dose-dependent reduction in renal blood flow and precipitate acute renal decompensation, particularly in patients with impaired renal function, heart failure, liver dysfunction, or those taking diuretics and ACE inhibitors. 7
Treatment with NSAIDs is not recommended in patients with advanced renal disease; if necessary, close monitoring of renal function is required. 7
Long-term NSAID administration can result in renal papillary necrosis and other renal injury. 7
Diabetes
Monitor blood glucose closely, as fever and infection can affect glycemic control independent of antipyretic therapy. 1
Maintain glucose in the range of 140-180 mg/dL in critically ill patients, avoiding and immediately treating hypoglycemia (<60 mg/dL). 1
Respiratory Disease
NSAIDs should not be administered to patients with aspirin-sensitive asthma due to risk of severe, potentially fatal bronchospasm. 7
Use NSAIDs with caution in patients with preexisting asthma due to cross-reactivity with aspirin. 7
For patients with abnormal chest radiograph, consider thoracic bedside ultrasound when expertise is available to identify pleural effusions and parenchymal pathology. 1
Antibiotic Therapy
Begin antibiotics within 1 hour when infection is suspected as the cause of fever, especially in unstable or deteriorating patients, as delay increases mortality from sepsis. 2, 4
Start antibiotics immediately if there are signs of hemodynamic instability, septic shock, immunocompromised state, suspected meningitis, or suspected cholangitis. 4
Stable, immunocompetent patients without signs of sepsis or organ dysfunction can be observed for 1-2 hours before antibiotics, but blood cultures must be obtained first and close monitoring maintained. 4
Direct therapy against likely pathogens based on suspected source, patient risk for multidrug-resistant organisms, and local susceptibility patterns. 2
Supportive Care
For hypotension, initiate immediate fluid resuscitation with 250-500 mL crystalloid boluses. 4
Monitor vital signs every 4 hours (every 2 hours if receiving pressors), pulse oximetry every 4 hours, and start oxygen if saturation is less than 92%. 1, 4
Maintain strict intake and output monitoring every 8 hours, perform neurological assessment every 8 hours, and obtain serial lactate measurements in unstable patients. 4
Assess for venous thromboembolism risk and provide appropriate prophylaxis with unfractionated heparin or low-molecular-weight heparin in immobilized patients. 1
Critical Pitfalls to Avoid
Never delay identification and treatment of the underlying infection while focusing on temperature control. 2, 3
Do not treat the thermometer reading rather than the patient's symptoms and overall comfort. 3, 5
Persistent fever alone in a stable patient is rarely an indication to alter antibiotics. 2
NSAIDs can cause serious gastrointestinal bleeding, ulcers, and perforation that may occur without warning and can be fatal; risk increases with prior ulcer history, corticosteroid use, anticoagulants, SSRIs, SNRIs, higher doses, longer duration, smoking, alcohol use, older age, and poor health. 7
NSAIDs can cause serious skin reactions including Stevens-Johnson Syndrome, toxic epidermal necrolysis, and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), which can be fatal; discontinue immediately if rash, fever, or signs of hypersensitivity develop. 7
Avoid NSAIDs in pregnant women at approximately 30 weeks gestation and later due to risk of premature closure of fetal ductus arteriosus; use between 20-30 weeks requires monitoring for oligohydramnios if treatment exceeds 48 hours. 7