High Fever & Chills
Medically Reviewed & Fact-CheckedBy MD, Emergency Medicine & Internal Medicine
Reviewed: 9/6/2026Overview
Fever (pyrexia) is a controlled elevation of core body temperature above the normal circadian range (>38.0°C or 100.4°F) mediated by hypothalamic prostaglandin E2 release in response to pyrogens.
Possible Causes
- Viral infections (Influenza, COVID-19, Dengue, Chikungunya)
- Bacterial infections (Pneumonia, Urinary tract infections, Enteric/Typhoid fever)
- Parasitic infections (Malaria)
- Inflammatory diseases and drug reactions
When to Seek Care
Seek immediate medical care if fever is accompanied by rash, stiff neck, confusion, inability to keep fluids down, or if an infant under 3 months has a temperature above 38.0°C.
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