What Blood Tests Should You Take During Fever: A Comprehensive Guide for All Age Groups
Confused about which tests to take during a fever? Learn about key fever blood tests—CBC, CRP, Dengue, Malaria—and how combo panels help detect the cause quickly for all age groups.
Written by
Last updated on 1st Aug, 2025
What Blood Tests Should You Take During Fever: A Comprehensive Guide for All Age Groups
Fever is one of the most common symptoms that bring people of all ages to the doctor. While it’s often caused by something simple like a viral infection or seasonal flu, it can also be the first sign of something more serious, such as dengue, malaria, typhoid, or even a bacterial infection. Understanding the root cause of a fever is essential to ensure timely and effective treatment. This is where fever blood tests come into play.
With modern diagnostic technology, a single fever blood test panel can include multiple critical tests, such as CBC (Complete Blood Count), CRP (C-reactive Protein), Dengue, and Malaria, helping healthcare providers pinpoint the underlying cause of the fever quickly and accurately. In this detailed guide, we’ll explain which blood tests are essential during a fever, what they reveal about your health, and how to choose the right test package, especially when you're unsure about the cause of your fever.
Why Blood Tests Are Crucial During a Fever?
Fever is a natural response of the body to an infection or inflammation. However, the cause of fever can range from mild viral infections to life-threatening illnesses. A physical examination alone may not be sufficient to identify the exact source. This is why doctors often rely on a set of blood tests for fever diagnosis.
These blood tests help:
- Differentiate between bacterial and viral infections
- Detect specific diseases like dengue, malaria, or typhoid
- Evaluate the severity of the infection
- Guide appropriate treatment decisions
Whether the patient is a child, an adult, or an elderly individual, timely blood testing during fever can significantly improve the outcome.
Most Common Fever Blood Tests You Should Know About
Fever is a common symptom that can be caused by a wide range of infections and underlying health conditions. To pinpoint the exact cause, doctors often rely on specific blood tests that reveal what’s happening inside your body. Here are the most common fever blood tests you should know about for accurate diagnosis and timely treatment:
1. CBC (Complete Blood Count)
The CBC is often the first test recommended during a fever episode. It evaluates three major types of cells in the blood: white blood cells (WBCs), red blood cells (RBCs), and platelets.
- Why it matters: Elevated or decreased WBC counts can suggest the presence of infection or inflammation. A low platelet count may indicate dengue or other viral infections.
- Ideal for: Initial screening in all age groups.
- Turnaround time: Results typically available within a few hours.
Schedule a Complete Blood Profile
2. CRP (C-Reactive Protein)
CRP is a marker of inflammation in the body. This test is useful to detect the presence and intensity of inflammation or infection.
- Why it matters: High CRP levels often point to bacterial infections and can help guide decisions on antibiotic use.
- Ideal for: Distinguishing between bacterial and viral infections, especially in children and elderly patients.
- Turnaround time: Results available on the same day in most labs.
Get Tested for Signs of Inflammation
3. Dengue NS1 Antigen
Dengue fever is prevalent during monsoon and post-monsoon seasons in India. The NS1 antigen test can detect dengue in the early stages, even before antibodies develop.
- Why it matters: Early diagnosis of dengue helps prevent severe complications such as dengue haemorrhagic fever or dengue shock syndrome.
- deal for: Patients with high-grade fever, especially if they live in or have travelled to dengue-prone areas.
- Turnaround time: Typically 24 to 48 hours.
Book a Dengue NS1 Antigen Test
4. Malaria Parasite Test (Peripheral Smear or Rapid Antigen Test)
Malaria, transmitted by mosquitoes, remains a concern in many parts of India.
- Why it matters: Detects the presence of malaria-causing parasites in the blood.
- deal for: Patients with recurring fever, chills, and sweating, especially after visiting rural or endemic areas.
- Turnaround time: Rapid tests provide results within 30 to 60 minutes; blood smear takes 24 hours.
5. Typhoid Test (Widal Test or TyphiDot)
Typhoid fever is a bacterial infection that spreads through contaminated food and water.
- Why it matters: Identifies antibodies against Salmonella bacteria. However, results must be interpreted alongside clinical symptoms and other tests.
- Ideal for: Persistent fever with digestive symptoms like constipation or diarrhoea.
- Turnaround time: 1 to 2 days.
6. Combo Panels: Fever Profile Test Packages
Many diagnostic labs now offer combo fever panels that combine several of the above tests in one convenient package. Here are the fever-related lab test panels available on Apollo 24|7, along with their names and overview:
A. Apollo Fever Panel – Basic: Includes 53 tests (CBC, LFT, ESR, CRP, urine routine, etc.) for evaluating general fever and infection markers.
Book an Apollo Fever Panel – Basic Test
B. Apollo Fever Panel – Essential: Includes 31 tests including Widal (typhoid), LFT, kidney, electrolytes, malaria smear, ESR, and other fever related tests.
Book an Apollo Fever Panel – Essential Test
C. Apollo Fever Panel – Complete: Includes 59 tests covering dengue, malaria, typhoid, CRP, CBC, urine routine, ESR, and other fever related tests.
Book an Apollo Fever Panel – Complete Test
D. Apollo Fever Panel – Comprehensive: Includes 68 tests (CRP, Typhidot, Chikungunya, Dengue IgG/IgM, malaria parasite, Widal, urine & CBC).
Book an Apollo Fever Panel – Comprehensive Test
Tips for Choosing the best panel test are:
- Basic: Good for general fever or follow-up.
- Essential: Adds specific screens for typhoid and malaria.
- Complete: Broad coverage including dengue testing.
- Comprehensive: Most in-depth, including chikungunya and antibody tests.
These comprehensive panels are ideal for patients with fever of unknown origin and save both time and money while increasing diagnostic accuracy.
Get Your Health Assessed Here
Member priceWhat Makes a Fever Panel with CBC, CRP, Dengue & Malaria the Best Choice?
The CBC, CRP, Dengue, and Malaria combo is considered the gold standard fever panel for several reasons:
Covers major tropical fevers: These are the most common causes of febrile illness in India.
- Early detection: NS1 antigen and CRP detect infection even before antibody response begins.
- Comprehensive yet targeted: Helps your doctor make evidence-based decisions and avoid unnecessary medications.
- Faster diagnosis: Reduces the need for multiple rounds of testing, which is especially helpful in children and elderly patients who may be more vulnerable to complications.
When Should You Take a Fever Blood Test?
You should consider getting a blood test for fever if:
- The fever persists for more than 3 days
- You have high-grade fever with chills, body ache, or rash
- There is no clear cause of fever from a physical exam
- You live in or have travelled to areas where dengue or malaria is common
- Your doctor recommends it to confirm or rule out a specific infection
Who Should Get Fever Blood Tests?
These tests are suitable for:
- Children: Especially under 5 years, as fever may indicate a serious infection
- Adults: To rule out dengue, malaria, or bacterial infections quickly
- Elderly: As fever could indicate underlying complications, including infections like pneumonia or urinary tract infections
- Immunocompromised individuals: Including those with diabetes, cancer, or on immunosuppressants
How to Prepare for a Fever Blood Test?
Most fever-related tests do not require fasting. However, if your doctor includes other tests like liver or kidney function tests, you may need to fast for 8–10 hours.
- Inform your doctor: About any current medications, as some may affect results.
- Stay hydrated: This makes blood sample collection easier.
- Follow instructions: Some combo packages may require special preparation, so always ask beforehand.
What Do the Test Results Mean?
Here’s a general guide to interpreting some of the key results:
Note: Always consult your doctor for interpretation. Self-diagnosing based on lab reports can be misleading.
What to Do After Getting the Test Results?
Once your fever blood test results are in:
- Consult your doctor to understand the report and next steps.
- Do not self-medicate based on the results.
- Start treatment promptly if an infection is diagnosed.
- Follow up with any additional tests as recommended.
- Monitor your symptoms, especially in children and elderly individuals.
Conclusion
Fever may seem simple, but the underlying cause can vary widely, from common viral infections to serious illnesses like dengue or malaria. A timely fever blood test, especially a comprehensive combo panel including CBC, CRP, Dengue, and Malaria, ensures rapid and accurate diagnosis. By choosing a trusted provider like Apollo 24|7, you gain access to advanced diagnostic services, certified labs, and home testing convenience, all crucial when you're feeling unwell or caring for a sick family member. Don’t ignore a persistent fever. Book your fever test today with Apollo 24|7 and get on the path to recovery faster.