What temperature counts as fever?
Fever is defined as an axillary (armpit) temperature above 38°C (100.4°F) or rectal temperature above 38.5°C. For babies under 2 years, rectal temperature is most accurate. Axillary and tympanic (ear) thermometers are acceptable for older children. Forehead (temporal artery) thermometers are convenient but less precise. Never use mercury thermometers due to breakage risk. Normal temperature varies throughout the day — lower in the morning, higher in the afternoon — and slightly between children.
Fever is actually a normal and beneficial immune response: the body raises its temperature to slow pathogen replication and activate immune cells. This means lowering fever doesn't "cure" the underlying infection — it improves the child's comfort. What matters most isn't the exact temperature but the child's overall state and any accompanying symptoms.
Key facts for parents
- ✓Any fever in a baby under 3 months requires immediate emergency evaluation — no exceptions
- ✓High temperature alone matters less than the child's general state: an active, drinking child is reassuring
- ✓Never give aspirin to children under 16 years old — risk of Reye syndrome (serious liver and brain damage)
- ✓Alternating paracetamol and ibuprofen should only be done under medical guidance to avoid dosing errors
- ✓Febrile convulsions (under 5 min) in children 6 months to 5 years are frightening but generally benign
Not sure what to do about your child's fever?
A physician can evaluate symptoms, advise whether home management is sufficient, or tell you when to go to the ER — online from S/80.
Consult now →Emergency warning signs — go to the ER immediately
Take your child to the emergency room immediately if you observe any of these: any fever in a baby under 3 months; difficulty breathing or very rapid breathing; purple or reddish spots on the skin that don't fade when you press them (petechiae or purpura — possible sign of meningococcal infection); stiff neck or extreme sensitivity to light; a seizure lasting more than 5 minutes, or a second seizure in the same fever episode; loss of consciousness or difficulty waking; blue lips or fingernails; inconsolable crying for more than 2 hours in an infant.
See a doctor within 24 hours (not necessarily the ER) if: fever is above 39°C in a 3–6 month old; fever lasts more than 3 days in an older child; the child is getting progressively worse despite antipyretics; there is severe ear pain, persistent vomiting preventing hydration, or signs of urinary tract infection (painful urination, strong-smelling urine). An online consultation can help you decide whether the situation warrants an in-person visit.
Get guidance from a doctor now
Online medical consultation from S/80. Available across all of Peru.
Book nowHome management of fever
The most important intervention is ensuring adequate hydration — offer fluids frequently (water, oral rehydration solution, breast milk). Dress the child lightly and keep the room cool but not cold. Lukewarm (not cold) baths can improve comfort. For antipyretics: paracetamol (15 mg/kg every 6–8 hours) is safe from birth; ibuprofen (10 mg/kg every 6–8 hours) from 6 months of age. Dose by weight, not age. Give antipyretics when the child has fever AND is uncomfortable — not as prevention or before the thermometer reaches 38°C.
Monitor the child closely, particularly: urinary output (normal urination is reassuring), ability to drink, responsiveness and playfulness. Viral fevers commonly last 3–5 days — this is normal. The child may feel better for a few hours after antipyretics, then fever returns as the dose wears off. This pattern is expected, not a sign of worsening. Call a doctor if fever persists beyond 5 days or the child's general state worsens.
FAQ
Can high fever damage my child's brain?
This is a very common fear, but fever from common infections does not damage the brain even at 40–41°C. Brain damage from heat occurs only at temperatures above 42°C, which virtually never happens with infectious fever. Febrile seizures are frightening but do not cause brain damage.
Does my child need antibiotics for fever?
Most childhood fever is caused by viral infections that resolve on their own and do not respond to antibiotics. Antibiotics are only needed for confirmed bacterial infections (strep throat, ear infections, UTIs, pneumonia). A doctor must evaluate and decide — parents should not pressure for antibiotic prescriptions for viral illnesses.
Can an online doctor evaluate fever in my child?
Yes, for many cases. The doctor evaluates accompanying symptoms, the child's age, and overall state to advise whether home management is safe or whether an in-person visit is needed. For emergency warning signs, always go directly to the ER without waiting for an online consultation.
What if my child has fever after vaccination?
Mild fever within 24–48 hours of a vaccine is common and normal — it signals the immune system is responding. Paracetamol can be given for comfort. If fever is high, persists beyond 48 hours, or there are other concerning symptoms, consult a physician to rule out coincidental infection.
Conclusion
Most childhood fever is a self-limiting viral infection that responds to hydration and antipyretics. The key is knowing the warning signs that require emergency care, and being able to consult a doctor quickly when you're unsure — without necessarily making a stressful ER trip for a routine fever.
At Delvir, you can consult a physician online from S/80, from anywhere in Peru.