My child has been waking from naps with fever all night and now has sudden vomiting without cough; what could be causing this and how should I manage her?

Immediate Assessment and Management

Your child needs urgent medical evaluation today—fever with sudden vomiting in a child without cough raises concern for serious bacterial infection (SBI), particularly urinary tract infection, and requires prompt assessment to rule out conditions like meningitis or other infections. 1

Key Red Flags Present

Your child has several concerning features:

• Recurrent fevers requiring repeated antipyretic dosing ("chasing fevers all night")
• Sudden onset vomiting without preceding symptoms
• Absence of cough (making respiratory viral illness less likely)
• Lethargy (excessive napping/sleeping)

These features warrant immediate medical attention, not home observation 1, 2.

Most Likely Diagnoses to Consider

Primary Concerns (in order of likelihood):

1. Urinary Tract Infection (UTI)

• Now the most common SBI in febrile children under 2 years (5-7% prevalence, up to 20% in uncircumcised males)
• Can present with fever and vomiting without any urinary symptoms
• E. coli causes 87.4% of cases 1

2. Viral Gastroenteritis

• Typically includes diarrhea (which you haven't mentioned)
• Usually has sudden onset with mild fever
• However, viral infection does NOT exclude concurrent bacterial infection 1

3. Meningitis or Other Serious Bacterial Infection

• Lethargy with fever is a warning sign
• Vomiting can be a presenting symptom of CNS infection 3

What Needs to Happen Now

Immediate Actions:

Go to urgent care or emergency department if your child has ANY of these:

• Appears toxic, septic, or apprehensive
• Inconsolable crying or excessive irritability
• Altered mental status or difficult to arouse beyond normal sleepiness
• Signs of dehydration (decreased urine output, no tears, dry mouth)
• Bilious (green) or bloody vomit
• Temperature ≥40°C (104°F) 3, 4

Expected Medical Evaluation:

For a well-appearing febrile child under 2 years, the physician should:

1. Obtain urine sample (catheterized or clean-catch, NOT bag specimen) for urinalysis and culture 1

   • This is the single most important test given the high prevalence of UTI

2. Assess hydration status using physical examination (best method)

   • The Clinical Dehydration Scale evaluates: general appearance, eyes, mucous membranes, and tears 2

3. Consider blood work if child appears ill or has high fever

   • Complete blood count, blood culture if indicated 1

4. Lumbar puncture may be needed if:

   • Child is under 3 months old
   • Signs of meningeal irritation
   • Altered mental status 1

Management Strategy

If Mild Dehydration from Vomiting:

• Oral rehydration therapy is first-line (as effective as IV fluids)
• Half-strength apple juice followed by preferred liquids
• Ondansetron (anti-nausea medication) may be prescribed to help keep fluids down 2, 3

If UTI is Diagnosed:

• Antibiotics will be started
• Follow-up urine culture to confirm clearance

If Viral Gastroenteritis:

• Supportive care with hydration
• However, 10% of UTIs occur with bacteremia, and 52% of bacteremia occurs with UTI 1—so testing is still needed

Critical Pitfall to Avoid

Do NOT assume this is "just a stomach bug" because:

• The absence of cough and diarrhea makes simple viral illness less likely
• In febrile children under 2 years, only 58% with bacteremia or meningitis appear clinically ill 1
• Multiple infections can coexist (9% of patients have infections at multiple sites) 1
• The lethargy you describe is concerning and needs evaluation

Bottom Line

Stop trying to manage this at home with fever medication alone. The combination of persistent fever requiring repeated dosing, sudden vomiting, lethargy, and absence of respiratory symptoms creates a clinical picture that requires medical evaluation to exclude UTI and other SBIs. The younger your child (especially if under 3 months), the more urgent this becomes 1, 5.