• 1 week ago

Causes of High Fever in Children

What Is a High Fever?

Fever is defined as a body temperature above 38°C (100.4°F), and a high fever is generally considered to be 38.5°C (101.3°F) or above. It’s not an illness in itself, but a symptom of the body’s immune system at work—often trying to fight off an infection.

In children, fevers are common and often harmless. However, the cause of the fever, its duration, and accompanying symptoms help determine whether it’s part of a mild illness or something more serious.

Common Causes of High Fever in Children

1. Viral Infections

The most frequent cause of high fever in children.

  • Examples: Flu, RSV, adenovirus, rotavirus, roseola
  • Symptoms: Fever with cough, runny nose, diarrhea, rash, or fatigue
  • Duration: Usually lasts 3–5 days
  • Treatment: Supportive (hydration, rest, fever reducers); no antibiotics

2. Bacterial Infections

Less common, but can cause higher, more persistent fever and may need urgent treatment.

Examples:

  • Strep throat
  • Urinary tract infections (UTI)
  • Pneumonia
  • Ear infections
  • Meningitis

Signs: Localized symptoms (sore throat, pain with urination, ear pain), worsening condition

Treatment: Antibiotics, prescribed only after evaluation

3. Post-Vaccination Fever

A mild fever may occur within 24–48 hours after routine vaccinations.

  • Typically low-grade
  • No additional symptoms beyond fussiness or mild discomfort
  • Treat with fever reducers only if needed

4. Teething

Often misunderstood—teething does not cause high fever.

  • Mild temperature elevation (<38°C) is possible
  • Look for drooling, gum swelling, and irritability instead of illness signs

5. Occult or “Hidden” Infections

When a child has a fever but no obvious symptoms, hidden infections should be considered.

  • Common example: Urinary tract infection
  • Especially in infants, urine testing is important for unexplained fever
  • Imaging or blood tests may be needed in recurring cases

Warning Signs: When Is a Fever Concerning?

Not every high fever signals danger. But combined with certain symptoms, it may suggest a serious condition.

Call your doctor or go to the emergency room if:

  • Fever >39.5°C (103.1°F) that doesn’t respond to medication
  • Fever lasting more than 3 days
  • Infants under 6 months with fever above 38°C (100.4°F)
  • Trouble breathing, fast or labored breathing
  • Extreme fatigue, unresponsiveness, or limp body
  • Poor feeding, dehydration (no urine, dry mouth)
  • Skin rash (especially purple or petechiae-like)
  • Seizure, stiff neck, or altered mental state

How Is the Cause of Fever Diagnosed?

Dr. Ekin Pasinlioğlu carefully evaluates the child’s age, medical history, physical exam, and symptoms. Depending on the situation, further tests may include:

  • Complete blood count (CBC) and C-reactive protein (CRP)
  • Urinalysis and urine culture
  • Strep test or throat culture
  • Chest X-ray (if pneumonia is suspected)
  • Stool tests for gastrointestinal symptoms
  • Viral panels during outbreak seasons

These help differentiate bacterial vs. viral causes, guiding whether antibiotics are needed.

What Can Parents Do at Home?

  • Take temperature regularly with a reliable thermometer
  • Keep your child hydrated
  • Dress lightly and keep the room cool
  • Use fever reducers only when necessary, based on comfort and age
  • Observe behavior: Is your child playing? Alert? Sleeping comfortably?

It’s not just the number on the thermometer—it’s the overall condition of your child that matters most.