If your baby has trouble breathing, turns blue, is hard to wake or is having a first seizure, call emergency services immediately; Vietnam's medical emergency number is 115. Do not wait to repeat the temperature or finish reading. A baby younger than three months with a temperature of 38°C or above needs urgent medical contact and assessment, even if still reasonably alert.
The short version
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Age and the baby's condition matter alongside temperature.
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A lower reading does not prove recovery, and recordkeeping must not delay emergency care.
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If home care is advised, obtain a clear monitoring and re-contact plan.
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Three action levels, not three diagnoses
Seek emergency help for serious breathing difficulty, reduced responsiveness, concerning colour change, a non-blanching rash or a first seizure. Do not wait for every sign or a higher temperature. Have another adult call and help responders reach you while you stay with the baby. Calling 115 does not guarantee identical response times everywhere; if connection fails, have someone contact the nearest emergency service directly.
NICE and NHS agree on age-related thresholds requiring assessment: 38°C or above under three months, and 39°C or above from three to six months. Contact medical care promptly rather than waiting until morning. At any age, poor feeding, dehydration, deterioration or serious caregiver concern also justify early help. Being below a threshold does not establish that a baby is safe.
Take a reading you can explain
NHS describes using a digital thermometer in the armpit for young children, following the device instructions. Record the number, time and measurement site; do not add or subtract a homemade correction. After a bath or heavy wrapping, a comfortable short pause may help a repeat reading if there are no danger signs. Measurement must not delay contacting care for a concerning or very young baby.
A clear call states the baby's age, the armpit reading and time, and current feeding and alertness. Say that a reliable reading is unavailable if that is true. Feeling hot is relevant information but different from a measured temperature. The professional needs the baby's condition and measurement context, not only the phrase very high fever or a series of unexplained numbers.
Look at the baby between readings
Compared with usual, does the baby respond, wake to feed and breathe comfortably? Fewer wet nappies, a dry mouth, fewer tears or sunken eyes may suggest dehydration and warrant urgent advice, as NHS guidance explains. Do not diagnose from one sign in isolation. If the baby is difficult to wake or struggling to breathe, use the emergency pathway rather than trying to manage fluids at home.
NIMO suggests a meaningful comparison for handover: since afternoon the baby has fed less than usual and nappies are less wet, rather than seems a little tired. If the last nappy time is unknown, say so; do not search rubbish while assessment is needed. Notes can reveal a trend, but the observations of the person currently with the baby remain important.
Home care needs a route back to help
If home observation is appropriate and the baby is alert enough to feed safely, continue breast milk or infant formula, using smaller opportunities as advised. Do not dilute formula. Keep clothing comfortable rather than wrapping to induce sweating or using cold treatment to force down temperature. Completing solid-food meals is not the priority while the baby is unwell.
Ask: What should we watch tonight, when should we measure again if needed, and when should we call back despite having been seen? Wait and see needs an endpoint. NHS advises assessment for fever lasting five days, but that is not permission to wait five days when earlier concerns exist. Illness can change after a consultation; new deterioration warrants renewed contact.
Medicine does not replace the assessment decision
This article gives no doses. If fever medicine is considered, confirm the product, concentration and use with a clinician or pharmacist for the baby's age, weight and condition. Do not improvise combinations, alternating medicines or adult products. Improved comfort or a lower reading does not exclude serious illness. Response to medicine is not a home test of whether assessment is necessary.
To reduce duplicated administration, NIMO suggests one shared note of the product and time used according to professional instructions, handed to the next caregiver. Retain the label and supplied measuring device. Take them to assessment if readily available, but do not delay departure to assemble every box. Imperfect information is preferable to postponed help.
If a seizure occurs
Call emergency services for a first seizure, one lasting more than five minutes, or breathing difficulty; do not wait for five minutes during a first seizure. NHS advises protecting the head, clearing hazards and noting timing when possible. Do not restrain the child or put anything in the mouth, including a spoon, fingers or medicine. Do not attempt feeding during the seizure.
Afterward, if breathing continues, follow dispatcher instructions for recovery positioning and watch breathing; if breathing is not normal, follow resuscitation guidance. Do not drive while trying to care for a still-seizing or unconscious child. Do not decide it was only a febrile seizure and skip assessment. A professional needs to establish what happened and what care follows.
A call that works at night
Begin a call with the baby's age, when fever started, the reading and measurement site, then the change worrying you most. A usable question is: Does my baby need assessment now, and where should we go? For an emergency call, give the address and access details early. Have another person gather papers or guide responders if available; do not search for the highest-rated facility while danger signs are present.
When the baby is well, prepare the thermometer, a clearly written address and a route to emergency care. Directory links can support advance planning; they are not substitutes for an emergency call during a crisis. Readiness does not mean managing every fever alone. It means recognizing when help is needed and being able to act while worried, tired or temporarily on your own.
Practical checklist
- Keep the thermometer and instructions in a known place.
- Save the address, 115 and a direct local emergency backup.
- For home observation, obtain return criteria and out-of-hours contact.
From the guide to your next step
How NIMO built this guide
NIMO writes and localizes each guide for Vietnamese families, then checks key facts against the official references below. The links support the guide; they are not the guide itself.
General health information · Checked against official sourcesFor symptoms or treatment decisions, confirm with an appropriate health professional.Next review · Dec 5, 2026
