Influenza (Flu) in Babies & Toddlers
Content reviewed against published CDC, AAP, CDC guidelines
Last reviewed:
Influenza (the flu) is a contagious respiratory illness caused by influenza viruses. In babies and toddlers, it can cause more severe illness than a common cold, including high fever, body aches, and extreme fatigue. Children under 5 (especially under 2) are at higher risk for serious flu complications.
Key takeaways
- Influenza (the flu) is a contagious respiratory illness caused by influenza viruses.
- Duration: Fever typically lasts 2-5 days. Most symptoms resolve in 7-10 days, though cough and fatigue may linger for 2 weeks.
- Go to ER if: Fast breathing or trouble breathing
- A vaccine or immunization is available
Symptoms
How It Presents by Age
0-6 months
May present with fever, poor feeding, irritability, and lethargy. Cough and congestion may be prominent. Cannot receive flu vaccine, so depend on maternal antibodies and household vaccination.
Risk level: High
6-12 months
High fever, irritability, poor feeding, and cough. May have vomiting. First flu season after vaccination begins.
Risk level: Moderate to high
1-2 years
Classic flu symptoms with high fever, misery, body aches (shown as fussiness and refusing to walk), and cough. May have febrile seizures.
Risk level: Moderate
2-5 years
More classic presentation with fever, cough, sore throat, and body aches. Can usually describe where they hurt.
Risk level: Moderate
Treatment
Antiviral medication (oseltamivir/Tamiflu)
Most effective if started within 48 hours of symptom onset. Recommended for all children under 2, and children at high risk. Available as liquid for infants.
Fever management
Acetaminophen for all ages; ibuprofen for 6+ months. NEVER give aspirin to children (risk of Reye syndrome).
Hydration
Push fluids — breast milk, formula, water, diluted juice, or electrolyte solutions. Small frequent sips.
Rest
Allow plenty of sleep. The body needs energy to fight the virus.
Home Care
- Offer plenty of fluids — breast milk, formula, water, or electrolyte drinks
- Use a cool-mist humidifier to ease congestion
- Saline nasal drops and gentle suctioning
- Dress in light layers to manage fever
- Lukewarm baths for comfort (not cold)
- Honey for cough in children over 1 year
- Keep child home and resting
When to Worry
Go to the ER if:
- Fast breathing or trouble breathing
- Bluish skin color
- Not drinking enough fluids or signs of dehydration
- Severe or persistent vomiting
- Child is not waking up or not interacting
- Seizure
- Fever above 104°F in a baby under 3 months
- Symptoms improve then return with worse fever and cough
Call your doctor if:
- Any baby under 6 months with suspected flu
- Fever lasting more than 3 days
- Ear pain or drainage
- Child not urinating at least every 8 hours
- Cough lasting more than 10 days
- To discuss antiviral medication (most effective within first 48 hours)
Keep an eye on:
- Fever over 104°F (40°C)
- Fever lasting more than 5 days
- Child seems to improve then gets worse again
- Rapid or difficult breathing
- Not drinking enough fluids
Prevention
- Annual flu vaccine for all children 6 months and older
- Two doses needed for first-time vaccine recipients under 9 years old
- Household members should all be vaccinated to protect infants under 6 months
- Frequent handwashing
- Avoid close contact with sick people
- Teach children to cough into their elbow
- Clean frequently touched surfaces
Contagion & Incubation
Incubation
1-4 days (average 2 days)
Contagious for
1 day before symptoms appear through 5-7 days after becoming sick. Young children may be contagious for longer than 7 days.
Duration
Fever typically lasts 2-5 days. Most symptoms resolve in 7-10 days, though cough and fatigue may linger for 2 weeks.
Frequently asked questions
How long does influenza (flu) last?
How does influenza spread?
When should I take my baby to the ER?
Can influenza be prevented?
When can my child return to daycare?
Sources
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources
Related Illnesses
Bottom line
Influenza (Flu) is a viral illness that typically resolves on its own. Seek emergency care if fast breathing or trouble breathing.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.