Treatment of Fever

1. The Decision to Treat

Fever itself is not a disease - it is a normal physiological response. Most fevers accompany self-limited infections. There is no clinical evidence that antipyretics delay resolution of viral or bacterial infections, or that fever meaningfully aids immune defense. Treating fever with routine antipyretics does no harm and does not slow recovery from common infections. - Harrison's Principles of Internal Medicine, 22E, p. 179

Situations where treating fever is highly recommended:

Patients with preexisting cardiac, pulmonary, or CNS impairment (fever raises oxygen demand by 13% for every 1°C above 37°C)
Children with a history of febrile or nonfebrile seizures
Hyperpyrexia (very high fever, typically >41°C)
CNS disease or trauma (high temperature worsens brain injury)

When withholding antipyretics may be useful:

To monitor antibiotic effectiveness in bacterial infections without positive cultures
To recognize characteristic fever patterns (e.g., tertian fever of P. vivax, quartan fever of P. malariae, Pel-Ebstein pattern in lymphoma)

2. Pharmacological Treatment (Antipyretics)

Acetaminophen (Paracetamol) - First-line preferred

Inhibits prostaglandin synthesis in the CNS, reducing the hypothalamic set point
Weak peripheral COX inhibition, so it has minimal anti-inflammatory and no antiplatelet effect
Does not affect platelet function or increase bleeding time
Preferred over aspirin and NSAIDs because it avoids GI and platelet adverse effects
Drug of choice in children with viral infections or chickenpox - aspirin must be avoided due to risk of Reye syndrome
Available orally, IV, and as rectal suppositories
Lippincott Illustrated Reviews Pharmacology, p. 1364

Adverse effects of acetaminophen:

At normal doses: few significant adverse effects
Overdose: depletes hepatic glutathione → NAPQI accumulates → hepatic necrosis
Higher risk of hepatotoxicity in: liver disease, alcoholism, viral hepatitis, chronic malnutrition
Antidote for overdose: N-acetylcysteine
Avoid in severe hepatic impairment

Aspirin (Acetylsalicylic acid)

Equally effective to acetaminophen as an antipyretic
Contraindicated in children (Reye syndrome risk with viral infections)
Adverse effects: GI irritation, platelet inhibition, GI bleeding
Harrison's, p. 180

NSAIDs (e.g., Ibuprofen, Naproxen)

Excellent antipyretics; inhibit COX enzymes, reducing PGE2 synthesis
Ibuprofen has improved efficacy over acetaminophen at reducing fever in children under 2 within the first 24 hours, with equivalent safety
Adverse effects: GI irritation, platelet dysfunction, risk of MI and stroke (especially COX-2 selective agents)
Parenteral NSAID preparations are available for patients who cannot take oral medication
Firestein & Kelley's Textbook of Rheumatology; Harrison's, p. 180

Glucocorticoids

Act at two levels: inhibit phospholipase A2 (reducing arachidonic acid release) and block transcription of pyrogenic cytokine mRNA
Potent antipyretics, but reserved for specific indications (autoimmune/autoinflammatory diseases, not routine fever)

3. Physical (Non-Pharmacological) Measures

Method	Notes
Tepid sponge bathing	Helpful when used alongside antipyretic therapy, not alone
Cooling blankets	Used in hyperpyrexia, but must not be used without oral antipyretics
Adequate hydration	Supports heat dissipation

Swanson's Family Medicine Review; Harrison's, p. 180

4. Goals of Treatment

The two main objectives are:

Reduce the elevated hypothalamic set point (pharmacological - antipyretics)
Facilitate heat loss (physical cooling measures)

Reducing fever also relieves systemic symptoms: headache, myalgias, and arthralgias.

5. Special Situations

Situation	Recommendation
Children (viral illness / chickenpox)	Acetaminophen or ibuprofen; avoid aspirin
Patients on anticytokine therapy	Even low-grade fever warrants early rigorous workup (febrile response is blunted)
Chronic glucocorticoid / NSAID users	Fever may be masked; do not be reassured by absence of fever
Neonates, elderly, chronic renal/liver failure	Fever may be absent even with serious infection
Periodic fever syndromes (e.g., FMF, TRAPS, NLRP3)	Require specific targeted therapies (e.g., colchicine, anakinra, canakinumab)
Sepsis	A meta-analysis showed antipyretic treatment was associated with lower 14-day mortality, though no significant benefit at 28 days

Sources: Harrison's Principles of Internal Medicine, 22nd Ed. (2025), pp. 179-180 | Lippincott Illustrated Reviews: Pharmacology, pp. 1363-1365 | Firestein & Kelley's Textbook of Rheumatology | Swanson's Family Medicine Review

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