Unexplained Fever in Infants and Children and When to Worry

Mother putting hands on a little girl's forehead

Medically Reviewed by Dr. Pang Yu Xian (M.B.B.S., Singapore)

Fevers are a common occurrence in infants and children, often indicating that the body is fighting an infection. However, when a fever persists without an apparent cause and its symptoms, it can be a source of concern for parents. Understanding when to worry about a fever and when to seek medical advice is crucial. 

This article explores the causes of unexplained fever in children, when to be concerned, and how to manage it effectively, focusing on the context of healthcare in Singapore.

Understanding Fever in Children

What is Fever?

A fever is defined as a temporary increase in body temperature, often due to an illness. In children, a fever is usually considered to be a temperature of 38°C (100.4°F) or higher. Fevers are a natural response of the immune system to infections, helping the body to fight off viruses and bacteria.

Common Causes of Fever

Fevers in children can be caused by a variety of factors, including:

  • Infections: Viral or bacterial infections are the most common causes of fever. Common infections include colds, flu, ear infections, and urinary tract infection.
  • Immunisations: Sometimes, children develop a mild fever after vaccinations as their bodies build immunity.
  • Overdressing: Infants, in particular, can develop a fever if they are overdressed or in a hot environment because their bodies are not yet efficient at regulating temperature.

When to Worry About Children Fever

Infants Under 3 Months

For infants under three months old, any fever above 38°C (100.4°F) is a cause for concern. Young infants are more vulnerable to serious infections, and a fever can be an early sign of a severe illness. Immediate medical attention is recommended.

Children Between 3 to 6 Months

In children aged three to six months, a fever above 38.3°C (101°F) should be evaluated by a healthcare provider. While it may not always indicate a serious condition, it’s important to rule out any potential health issues.

Persistent Fever

If a child of any age has a fever that lasts more than three days, it warrants a visit to the doctor. Persistent fever can be a sign of an underlying infection that needs medical treatment.

High Fever

A fever that exceeds 40°C (104°F) is considered high and can be dangerous. Such high temperatures can lead to complications, and immediate medical attention is necessary to bring the fever under control and identify the cause.

Other Warning Signs

Seek medical attention if a fever is accompanied by any of the following symptoms:

  • Difficulty breathing or rapid breathing
  • Severe headache or stiff neck
  • Persistent vomiting or diarrhea
  • Unusual rash
  • Unresponsiveness or difficulty waking
  • Seizures
  • Signs of dehydration, such as dry mouth, no tears when crying, and fewer wet diapers

Managing Fever at Home

Hydration

Keeping your child well-hydrated is crucial when they have a fever. Offer plenty of fluids, such as water, oral rehydration solutions, or breast milk/formula for infants, to prevent dehydration.

Comfort Measures

Dress your child in lightweight clothing and keep their room comfortably cool. Avoid overdressing or using heavy blankets, as this can raise their body temperature.

Medication

Over-the-counter medications such as acetaminophen (paracetamol) or ibuprofen can help reduce fever and alleviate discomfort. Always follow the dosage instructions on the label or as provided by your healthcare provider. Do not give aspirin to children, as it can cause a rare but serious condition called Reye’s syndrome.

Rest

Encourage your child to rest and avoid strenuous activities. Rest helps the body fight off infections more effectively.

When to See a Doctor

Immunocompromised Children

Children with weakened immune systems, such as those undergoing chemotherapy or with chronic illnesses, should see a doctor promptly if they develop a fever.

Infants with Fever

As mentioned earlier, infants under three months old with a fever should be seen by a healthcare provider immediately. For infants between three and six months old, any fever above 38.3°C (101°F) should be evaluated.

Persistent or High Fever

A fever that lasts more than three days or exceeds 40°C (104°F) requires medical attention. Your doctor will conduct a thorough examination and may order tests to determine the cause of the fever.

Preventing Infections

Vaccinations

Ensure your child is up-to-date with their vaccinations. Vaccines are a critical tool in preventing many serious infections that can cause fever.

Hand Hygiene

Teach your child the importance of washing their hands regularly with soap and water, especially before eating and after using the bathroom.

Avoiding Sick Contacts

Limit your child’s exposure to individuals who are sick, especially during flu season. Encourage good respiratory hygiene, such as covering the mouth and nose with a tissue or elbow when coughing or sneezing.

Get Expert Help for Unexplained Fevers in Children: Consult with Keystone Clinic & Surgery Today!

It is not uncommon that children can get infections every 6-8 weeks especially when their immune system is just developing. Understanding when to worry about a fever in infants and children can help parents make informed decisions about seeking medical care. While fevers are often a natural part of the body’s defense against infections, certain signs and symptoms indicate the need for professional evaluation. By staying informed and proactive, parents can ensure their children’s health and well-being. 

If your child is experiencing an unexplained fever and you are unsure about the next steps, don’t hesitate to seek professional medical advice. Keystone Clinic & Surgery offers comprehensive pediatric care to help diagnose and manage fevers and other health concerns. Visit us to learn more and schedule a consultation with our experienced healthcare providers. 

References

Children’s National Hospital. Pediatric Fever of Unknown Origin. https://www.childrensnational.org/get-care/health-library/fever-of-unknown-origin

Harvard Health Publishing. 2020. When to Worry About Your Child’s Fever. https://www.health.harvard.edu/blog/worry-childs-fever-2017072512157

Ncbi.nlm.nih.gov. 2017. Fever in Children: Pearls and Pitfalls. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615271/

Ncbi.nlm.nih.gov. 2003. Unexplained Fever in Young Children: How to Manage Severe Bacterial Infection. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC261750/