Fever Symptoms: Recognizing Signs in Adults & Children

Fever = core temperature ≥100.4°F (38°C). It is a symptom, not a disease—indicating immune activation, usually from infection.

Common Accompanying Signs & Symptoms

• Sweating (diaphoresis)
• Chills, rigors (shaking chills = bacteremia clue)
• Headache
• Myalgia, arthralgia
• Fatigue, malaise
• Anorexia
• Irritability (especially children)
• Tachycardia (~10 bpm per 1°F rise)
• Flushed skin, warm to touch

Red Flags (Seek Urgent Care)

• Temp ≥104°F (40°C) or ≥100.4°F in infant <3 months
• Altered mental status, confusion, lethargy
• Stiff neck, photophobia (meningitis)
• Rash (petechial/purpura = meningococcemia)
• Dyspnea, chest pain
• Seizure
• Signs of dehydration
• Fever >3 days without clear source

Measurement Notes

Rectal most accurate (core). Oral, tympanic, temporal acceptable. Axillary least reliable. Document method.