Child Fever Duration by Cause: Viral, Bacterial, Teething

Cause	Low-Grade (100.4–102.2°F)	Moderate (102.3–104°F)	High (>104°F)
Viral	3–4 days	2–3 days	≤24–36 hrs
Bacterial	5–7 days	3–5 days	2–3 days
Teething	1–2 days	Rare	Rare

Persistent high fever >3–5 days or >104°F needs medical evaluation. Guidelines only; individual variation exists.