Viral fever, dengue or typhoid? How doctors tell the difference
Written by Dr. Vishnu Anjan Nareddy, MD (General Medicine)Professor of Medicine-Senior consultant physician (MD, General Medicine) · 5 min readThe short answer
When a fever strikes, knowing whether it is a self-limiting viral fever, dengue needing platelet monitoring, or bacterial typhoid requiring antibiotics is critical. Doctors use fever patterns, specific clinical symptoms, and lab test timing to make the correct diagnosis.
Fever patterns: how they behave differently
- Viral Fever: Sudden high onset (101°F–103°F) with runny nose, throat irritation, and body pain. Peaks on days 1–2 and settles by day 4.
- Dengue: Sudden intense fever accompanied by severe pain behind the eyes, bone aches ('breakbone fever'), and nausea. Platelet drops begin around days 3–6.
- Typhoid: Slow, step-ladder fever rising higher day after day, accompanied by abdominal pain, headache, and severe fatigue.
The golden rule of fever blood tests
- Days 1–3 of fever: Complete Blood Count (CBC) and Dengue NS1 antigen test are most accurate.
- Days 4–7 of fever: Repeat CBC for platelets, Dengue IgM antibodies.
- Fever beyond 5–7 days: Blood culture and Widal test for Typhoid, urine routine.
Hydration strategy for all fevers
Drink plenty of ORS, tender coconut water, and soups. Keep a written log of daily fluid intake and urine frequency. Adequate urine output is the best indicator of internal hydration.
Have a fever for more than 2 days?
Get your blood test done and consult our doctors in a single visit. Open until 10 pm.
Book a fever checkThis guide is general information and not a diagnosis. Reviewed by Dr. Vishnu Anjan Nareddy · October 2026 · How we write and review guides