Fever for more than 2–3 days? Tests doctors commonly order

Most fevers are viral and settle in 2–3 days with rest and fluids. When fever continues beyond that, or comes with body ache, chills or rash, doctors usually want blood tests to look for dengue, malaria, typhoid or a urine infection – especially during the monsoon. Getting tested at the right day of fever makes results more useful.

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Tests to ask about

CBC with platelet count

First test in fever – shows infection pattern and platelet count.

₹330 Book Details

Dengue NS1 / IgM

NS1 in the first 5 days, IgM after that.

₹765 Book Details

Malaria test

For fever with chills, especially in the monsoon.

₹680 Book Details

Typhoid test (Widal / Typhidot)

For fever lasting a week with stomach symptoms.

₹264 Book Details

Urine routine

Checks for urine infection as a cause of fever.

₹180 Book Details

CRP

Helps judge how strong the infection or inflammation is.

₹525 Book Details

Common reasons doctors look for

Viral fever, including flu
Dengue – high fever, severe body ache, pain behind eyes
Malaria – fever with chills that comes and goes
Typhoid – fever that rises day by day, with stomach upset
Urine infection – fever with burning urination
Chest or throat infection

How to prepare

Fever tests need no fasting. Tell the collector which day of fever it is: dengue NS1 is most useful in the first 5 days, while dengue antibody and typhoid tests are more useful after about 5–7 days.

When to see a doctor

Go to a doctor or hospital immediately if fever comes with bleeding from gums or nose, red spots on skin, severe stomach pain, repeated vomiting, confusion, stiff neck, fits, difficulty breathing or very little urine. Fever in babies under 3 months always needs a doctor.

Fever – FAQs

Which test should I do for fever?

A CBC with platelet count is the usual first test. Doctors add dengue NS1 or antibodies, malaria test, typhoid test and urine routine depending on symptoms and season.

When should the dengue test be done?

NS1 antigen is best in the first 1–5 days of fever. IgM antibodies usually turn positive after about 5 days.

Is the Widal test reliable for typhoid?

Widal can give false positives, especially early. Doctors interpret it with symptoms and sometimes advise a blood culture.

Why does platelet count matter?

In dengue, platelets can fall. Doctors often repeat the CBC to watch the trend.

This page is general information, not medical advice or a diagnosis. Please talk to a doctor about your symptoms.