fever specialist tests overview

Overview

A fever is a temporary rise in body temperature, often a sign that your body is fighting an infection. When a fever continues for a long time or comes back, doctors may order 'fever specialist tests' to find the cause. These tests help identify what is making you sick so the right treatment can begin.

Yes, fever is very common. Almost everyone gets a fever at some point, especially during infections like colds or flu. Needing specialist tests for a fever is less common and usually reserved for persistent or unexplained fevers.

Fever can affect people of all ages—infants, children, adults, and older adults. The need for specialist tests may be more likely in people with weakened immune systems, chronic illnesses, or very young or very old age.

Symptoms

Common symptoms

• Raised body temperature (usually above 38°C or 100.4°F)
• Sweating, chills, or shivering
• Headache, muscle aches, or feeling weak
• Loss of appetite, tiredness

Symptoms in children

• Irritability or fussiness
• Poor feeding or dehydration (fewer wet nappies)
• Faster breathing or heartbeat
• Fever that lasts more than 3 days

Symptoms in older adults

• Confusion or dizziness
• Loss of appetite or weakness
• Less obvious fever – temperature may not be very high
• Worsening of existing health conditions

Causes

Main causes

• Infections: bacterial (like pneumonia, urinary tract infections), viral (like flu, COVID-19), fungal, or parasitic
• Inflammatory conditions: such as rheumatoid arthritis or lupus
• Heat stroke or overheating
• Certain medicines (drug fever) or vaccines
• Rare causes: cancers (like lymphoma), blood clots, or thyroid problems

Risk factors

• Age: very young or very old
• Weakened immune system (due to illness or medications)
• Recent surgery or hospital stay
• Travel to areas with different infections
• Chronic diseases (diabetes, heart disease, etc.)

When to see a doctor

See a doctor urgently if:

• Fever with any of the emergency symptoms listed above (call emergency services)
• Fever in a baby younger than 3 months (always see a doctor urgently)
• Fever that is very high (above 40°C/104°F) and not responding to paracetamol or ibuprofen (used according to instructions)
• Fever with a stiff neck, confusion, or severe headache

Book a routine appointment if:

• Fever that lasts more than 3 days without a clear cause
• Recurring fevers (come and go over weeks)
• Fever with unexplained weight loss or night sweats
• Fever after a recent tick bite or travel

Diagnosis

Your doctor will start by asking about your symptoms, medical history, and any recent travel or exposures. They will check your temperature and do a physical exam. If the cause is not clear, they may order specialist tests to find out why you have a fever.

Tests that may be done

• Blood tests: such as full blood count (to check for infection), blood cultures (to grow bacteria), or tests for inflammation (CRP, ESR)
• Urine tests: to check for a urinary tract infection
• Throat or nose swabs: to test for viruses like flu or COVID-19
• Imaging tests: chest X-ray, CT scan, or ultrasound to look for infections or other problems in organs
• Lumbar puncture (spinal tap): in some cases, to check for meningitis or encephalitis, especially if there is a stiff neck or confusion

What to expect at your appointment

Most tests are straightforward. Blood tests involve a needle in your arm, which may sting briefly. Swabs are quick. Imaging scans are painless. Your doctor will explain each test and why it is needed. Results may take a few hours to a few days, depending on the test.

Treatment

Treatment depends on the cause of the fever. If an infection is found, antibiotics or antiviral medicines may be prescribed. If inflammation is the cause, anti-inflammatory treatments might be used. For many mild fevers, no specific treatment is needed—just rest and fluids.

Self-care at home

• Rest as much as possible to help your body recover.
• Drink plenty of fluids (water, clear soups) to stay hydrated.
• Use a damp cloth on your forehead or take a lukewarm bath (not cold) to feel more comfortable.
• Over-the-counter fever reducers like paracetamol or ibuprofen can help lower temperature and ease aches—follow the instructions on the packet and check with a pharmacist if unsure.

Medical treatments

If a specific cause is found, your doctor will treat that cause. For bacterial infections, this usually means antibiotics. For viral infections, antiviral medications may sometimes be used. For inflammatory conditions, treatments such as corticosteroids or other medicines that reduce inflammation might be prescribed. Always take medicines exactly as your doctor advises.

When is surgery considered?

Surgery is very rarely needed for a fever itself, but it may be required if the fever is caused by an infection that needs draining (like an abscess) or a surgical problem (like appendicitis).

Living with this condition

If you have a fever that keeps coming back, it can be tiring. Listen to your body and rest when you need to. Keep a symptom diary to share with your doctor, noting when fevers happen and any other symptoms.

Lifestyle tips

• Maintain a healthy sleep routine to support your immune system.
• Manage stress with relaxation techniques like deep breathing or gentle exercise when you feel well enough.
• Stay connected with family and friends for emotional support.

Diet and exercise

Eat a balanced diet with plenty of fruits and vegetables to support your immune system. Stay hydrated. Avoid strenuous exercise when you have a fever, but gentle movement like short walks can be okay as you recover.

Mental health and emotional wellbeing

Having an unexplained or long-term fever can be worrying and stressful. It is normal to feel anxious or frustrated. Talk to your doctor about your concerns—they can offer support and refer you to a counsellor if needed.

Prevention

Not all fevers can be prevented, but you can reduce your risk of infections by practising good hygiene, such as washing hands regularly, avoiding close contact with sick people, and cooking food thoroughly.

Vaccines

Vaccines can prevent many infections that cause fever, such as flu, COVID-19, pneumonia, and meningitis. Talk to your doctor about recommended vaccinations for your age and health.

Screening programmes

There is no routine screening for fever itself, but if you have a condition that makes you prone to certain infections (like a weakened immune system), your doctor may recommend regular check-ups or tests.

Complications

If left untreated

• If the underlying cause of a fever is serious and not treated, it could lead to complications such as sepsis (a life-threatening response to infection), organ damage, or worsening of the original condition.
• In infants, a very high fever can sometimes cause febrile seizures (convulsions), which look scary but are usually not harmful with proper care.
• Prolonged fever may lead to dehydration, weight loss, or fatigue.

Long-term outlook

For most people, a fever is a short-lived problem that gets better on its own or with simple treatment. When specialist tests find a clear cause, treatment is usually effective, and the outlook is good. Even when the cause takes longer to find, modern medicine has many ways to manage fevers and improve symptoms. With the right care, most people recover fully.

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