Fever in Children: Symptoms, Causes & When to Seek Care

What Is Fever in Children?

Fever is defined as a body temperature of 38°C (100.4°F) or higher. It is the body's natural immune response to infection, helping white blood cells fight pathogens more effectively. Fever itself is rarely dangerous and is one of the most common reasons parents seek medical care for their children.

Fever is not an illness but rather a symptom that indicates the body's immune system is actively working to combat an infection or other condition. When your child has a fever, their body is raising its internal thermostat to create an environment less favorable for viruses and bacteria to thrive. This elevated temperature also enhances the function of immune cells, helping them work more efficiently to eliminate the infection.

Understanding what constitutes normal body temperature is essential for parents. Normal body temperature varies throughout the day, typically being lower in the morning and higher in the late afternoon. It also varies slightly depending on where and how temperature is measured. The commonly cited "normal" temperature of 37°C (98.6°F) is an average, and healthy children may have baseline temperatures slightly above or below this value.

The degree of fever does not necessarily correlate with the severity of the underlying illness. Some mild viral infections can cause high fevers, while serious bacterial infections may present with only low-grade temperature elevations. This is why healthcare providers emphasize assessing your child's overall condition and behavior rather than focusing solely on the thermometer reading.

Temperature Classifications

Healthcare providers typically classify fever into categories that help guide management decisions. A low-grade fever ranges from 38°C to 38.4°C (100.4°F to 101.1°F) and often requires minimal intervention beyond ensuring adequate fluid intake. Moderate fever, between 38.5°C and 39.4°C (101.2°F to 102.9°F), may benefit from fever-reducing medication if the child is uncomfortable. High fever, defined as 39.5°C to 40.5°C (103°F to 104.9°F), warrants closer monitoring and typically necessitates treatment to improve comfort. Very high fever above 40.5°C (105°F) requires prompt medical evaluation.

What Causes Fever in Children?

The most common cause of fever in children is viral infection, accounting for the vast majority of cases. Other causes include bacterial infections, immunizations, teething (rarely causing temperatures above 38.3°C), overdressing in infants, and less commonly, inflammatory conditions or heat exhaustion.

Viral infections are responsible for most fevers in children. Common culprits include respiratory viruses such as those causing colds, influenza, and respiratory syncytial virus (RSV), as well as gastrointestinal viruses that cause vomiting and diarrhea. These infections typically run their course within a few days to a week and do not require antibiotic treatment. The fever associated with viral infections often rises and falls over several days before resolving completely.

Bacterial infections, while less common than viral causes, require prompt identification because they often need antibiotic treatment. Common bacterial infections in children include strep throat, ear infections, urinary tract infections, and pneumonia. These conditions may present with fever along with specific symptoms related to the affected body system. Your child's healthcare provider can often distinguish between viral and bacterial infections through careful examination and, when necessary, diagnostic tests.

Immunizations frequently cause fever as a side effect, particularly within the first 24 to 48 hours after vaccination. This fever response indicates that the immune system is responding appropriately to the vaccine and building protection against the targeted disease. Post-vaccination fever is typically mild and resolves quickly. Some vaccines, such as the measles-mumps-rubella (MMR) vaccine, may cause fever 7 to 12 days after administration as the weakened live viruses stimulate immune response.

Less Common Causes

While infection is by far the most common cause of fever in children, other conditions can also elevate body temperature. Inflammatory diseases such as juvenile idiopathic arthritis or inflammatory bowel disease can cause recurrent or persistent fever. Certain medications may trigger drug fever as a side effect. In rare cases, malignancies can present with unexplained fever. Heat stroke or heat exhaustion, distinct from true fever, occurs when the body overheats due to environmental factors and represents a medical emergency.

Teething is often blamed for fever in infants, but research suggests this association is largely a myth. While teething may cause a very slight elevation in temperature, typically not exceeding 38.3°C (101°F), higher fevers during teething are more likely due to coincidental viral infections that are common in this age group. Parents should not dismiss significant fever as "just teething" without considering other potential causes.

What Symptoms Does Fever Cause in Children?

Children with fever may feel warm to touch, have flushed cheeks, sweating, chills, or shivering. They often become irritable, tired, have reduced appetite, and may complain of headache or body aches. Some children remain active and playful despite significant fever, while others feel unwell with even mild temperature elevation.

The symptoms accompanying fever vary considerably from child to child and do not always correlate with the degree of temperature elevation. Some children appear remarkably well and continue their normal activities despite having temperatures of 39°C or higher. Others become noticeably unwell with even mild fever, requiring rest and comfort measures. This individual variation is important to recognize, as your child's overall behavior and condition matter more than the specific temperature reading.

Physical signs of fever include skin that feels warm or hot to the touch, particularly on the forehead and abdomen. Cheeks may appear flushed or red. As the fever rises, children often experience chills or shivering as the body attempts to generate heat to reach its new temperature set point. Once the fever peaks, sweating typically occurs as the body works to dissipate excess heat. Some children experience pallor or a mottled appearance to their skin during fever.

Behavioral changes commonly accompany fever in children. Irritability and fussiness are particularly common in infants and toddlers who cannot verbally express discomfort. Older children may complain of headache, body aches, or general malaise. Appetite typically decreases during fever, which is normal and should not cause excessive concern as long as fluid intake remains adequate. Sleep patterns often change, with some children sleeping more than usual while others have difficulty settling.

Symptoms Requiring Immediate Attention

While most fevers are benign, certain accompanying symptoms warrant immediate medical evaluation. A stiff neck combined with fever may indicate meningitis, particularly if the child is also sensitive to light or has a severe headache. A rash that does not fade when pressed, known as a non-blanching or petechial rash, can indicate serious bacterial infection and requires urgent assessment. Difficulty breathing, persistent vomiting preventing fluid intake, or signs of dehydration such as no tears when crying, dry mouth, or significantly reduced urination all require prompt medical attention.

When Should You Seek Medical Care for a Child with Fever?

Seek immediate medical care if your child is under 3 months with any fever, has difficulty breathing, develops a non-blanching rash, is unusually drowsy or difficult to wake, shows signs of dehydration, or has a fever lasting more than 5 days. Trust your parental instincts - if you are worried, seek advice.

The decision to seek medical care for a febrile child depends more on the child's overall condition, age, and accompanying symptoms than on the height of the fever alone. However, certain situations always warrant prompt medical evaluation regardless of how the child appears. Understanding these red flags helps parents make informed decisions about when home care is appropriate and when professional assessment is needed.

Age is one of the most important factors in determining the urgency of fever evaluation. Infants under 3 months of age with any fever of 38°C (100.4°F) or higher require immediate medical assessment, typically in an emergency department. This is because young infants have immature immune systems and may not show typical signs of serious infection. They can deteriorate rapidly, and serious bacterial infections, though uncommon, must be promptly identified and treated. For infants between 3 and 6 months, fever above 39°C (102.2°F) warrants same-day medical evaluation.

Beyond infancy, the focus shifts to the child's overall condition and specific symptoms rather than temperature alone. A child who is alert, interactive, and drinking fluids adequately can often be monitored at home even with moderately high fever. However, a child who appears seriously unwell, is difficult to console, or shows concerning symptoms should be evaluated regardless of the temperature reading.

Signs That Warrant Same-Day Medical Evaluation

Certain situations, while not emergencies, still require medical assessment within the same day. These include fever lasting more than 5 days, fever returning after the child appeared to be recovering, persistent crying or irritability that cannot be soothed, refusing to drink fluids for several hours, signs of ear pain such as pulling at ears or increased crying when lying down, and fever accompanied by repeated vomiting or diarrhea. Children with underlying health conditions, including heart disease, immune disorders, or cancer, should have a lower threshold for medical evaluation when febrile.

How Do You Measure a Child's Temperature Correctly?

Rectal measurement is most accurate for infants under 3 months. For older children, ear (tympanic) and forehead (temporal artery) thermometers offer convenient and reasonably accurate readings. Armpit (axillary) measurement is least accurate but safest and may be useful for screening. Always follow the manufacturer's instructions for your specific thermometer.

Accurate temperature measurement is essential for assessing fever and monitoring your child's condition. Different methods have varying levels of accuracy, and the best choice depends on your child's age, cooperation level, and the clinical situation. Understanding how to use each method correctly ensures you obtain reliable readings that help guide your decisions about care.

Rectal temperature measurement provides the most accurate core body temperature and remains the gold standard for infants under 3 months of age, when precision is most critical. To measure rectally, use a digital thermometer with a flexible tip, apply a small amount of petroleum jelly, and insert gently about 1-2 centimeters (half to one inch) into the rectum while the baby lies face down or on their back with legs raised. Hold the thermometer in place until it beeps, typically 10-30 seconds. Always clean the thermometer before and after use.

Ear (tympanic) thermometers measure infrared heat from the eardrum and are popular for children over 6 months of age. These provide quick readings, usually within 1-2 seconds. For accurate results, gently tug the ear backward (in children over 1 year) or straight back (in infants) to straighten the ear canal, ensuring the probe is pointed toward the eardrum. Ear infections or excessive earwax may affect accuracy. Some newer models are designed to provide accurate readings regardless of positioning.

Forehead (temporal artery) thermometers scan across the forehead or temple to detect heat from blood vessels near the skin surface. These are convenient, non-invasive, and well-tolerated by children of all ages. For best results, ensure the forehead is dry and free from sweat, and follow the specific instructions for your device, as technique varies between models. While convenient, these may be slightly less accurate than rectal or ear measurements.

What About Other Methods?

Armpit (axillary) measurement is the least invasive method but also the least accurate, typically reading 0.5-1°C (1-2°F) lower than core temperature. It can be useful for initial screening or when other methods are not practical, but may miss low-grade fevers. To improve accuracy, ensure the thermometer tip is positioned deep in the armpit with the arm held snugly against the body for the full measurement time, typically 3-5 minutes for older thermometers or until beep for digital ones.

Oral temperature measurement is suitable for children old enough to hold the thermometer under their tongue with mouth closed, typically around 4-5 years of age. Place the thermometer tip under the tongue toward the back, close to the heat pocket under the tongue base. Have your child keep lips sealed until the reading completes. Avoid measuring immediately after eating or drinking hot or cold substances.

How Is Fever in Children Treated?

Fever treatment focuses on improving comfort rather than achieving a normal temperature. Paracetamol (acetaminophen) and ibuprofen are the primary medications used. Ensure adequate fluid intake, dress your child in light clothing, and keep the room comfortably cool. Never use aspirin in children due to risk of Reye's syndrome, and avoid cold baths or alcohol rubs.

The approach to treating fever has evolved significantly, with current guidelines emphasizing comfort rather than aggressively reducing temperature. Fever itself is beneficial, helping the body fight infection, and there is no evidence that treating fever shortens the duration of illness or prevents febrile seizures. The primary goals of treatment are to help your child feel better, maintain adequate hydration, and allow rest necessary for recovery.

Paracetamol (acetaminophen) is the most commonly used fever-reducing medication for children. It is safe for infants from 2-3 months of age (after first vaccinations) when dosed correctly based on weight. Paracetamol works by affecting the brain's temperature-regulating center and provides 4-6 hours of relief. Always use the measuring device provided with the medication rather than household spoons, and carefully follow weight-based dosing on the package or from your healthcare provider. The maximum daily dose should never be exceeded, as overdose can cause serious liver damage.

Ibuprofen is another effective fever reducer that also provides anti-inflammatory effects. It can be used in children from 3-6 months of age (depending on local guidelines) who weigh at least 5 kg. Ibuprofen should be given with food to reduce stomach upset and provides 6-8 hours of relief. It should be avoided in children who are dehydrated, have kidney problems, or have certain stomach conditions. Unlike paracetamol, ibuprofen is not recommended for chickenpox due to potential increased risk of skin complications.

Alternating Medications

In some cases, paracetamol and ibuprofen may be alternated when one medication alone does not provide adequate relief. However, this should not be done routinely and only when truly necessary, as it increases the risk of medication errors. If alternating, maintain at least 4 hours between paracetamol doses and at least 6 hours between ibuprofen doses. Keep a written log of what medication was given and when to avoid accidental overdose. Consult your healthcare provider or pharmacist if you have questions about this approach.

Non-Medication Approaches

Several non-pharmacological measures can help your febrile child feel more comfortable. Dress your child in lightweight clothing and avoid bundling up, which can trap heat and make fever higher. Keep the room at a comfortable temperature, neither too hot nor too cold. Offer plenty of fluids to prevent dehydration, which is especially important during fever as the body loses more water through sweating and increased respiratory rate. Water, diluted juice, oral rehydration solutions, and breast milk or formula for infants are all appropriate choices.

A lukewarm (not cold) sponge bath may provide temporary comfort by promoting heat loss through evaporation. However, if your child shivers during sponging, stop immediately as shivering generates heat and can actually raise body temperature. Never use cold water, ice, or alcohol rubs, as these can cause shivering, skin damage, or alcohol absorption through the skin. Cool compresses on the forehead or back of the neck may feel soothing but have minimal effect on core body temperature.

What Are Febrile Seizures?

Febrile seizures are convulsions triggered by fever, affecting 2-5% of children between 6 months and 5 years of age. They are caused by rapid temperature changes rather than fever height and, while frightening to witness, simple febrile seizures lasting less than 15 minutes are not harmful and do not cause brain damage or increase epilepsy risk.

Febrile seizures are one of the most frightening experiences for parents, but understanding them helps reduce anxiety and ensures appropriate response. These seizures occur in young children, typically between 6 months and 5 years of age, when fever rises rapidly. The seizure appears to be triggered by the speed of temperature change rather than how high the fever gets, which is why they often occur early in an illness before parents even realize their child has fever.

During a simple febrile seizure, the child may lose consciousness, stiffen, and then experience jerking movements of the arms and legs. The eyes may roll back, and the child may foam at the mouth or turn slightly blue. These seizures typically last less than 5 minutes, with most lasting only 1-2 minutes. After the seizure ends, children are often sleepy or confused for a short time but recover completely without any lasting effects.

Simple febrile seizures, which are the most common type, do not cause brain damage, do not affect intelligence, and do not significantly increase the risk of developing epilepsy. About one-third of children who have a febrile seizure will have another one with future fevers, with the risk highest in those who have their first seizure under 15 months of age. Children typically outgrow the tendency to have febrile seizures by age 5-6 years.

What to Do During a Febrile Seizure

If your child has a febrile seizure, try to stay calm. Place your child on their side on a safe surface to prevent choking. Do not put anything in their mouth, restrain them, or try to stop the movements. Note the time the seizure started. Most seizures stop on their own within a few minutes. Call emergency services if the seizure lasts longer than 5 minutes, your child has trouble breathing afterward, or this is your child's first seizure. After a first febrile seizure, have your child evaluated by a healthcare provider to confirm the diagnosis and rule out other causes.

Can You Prevent Fever in Children?

While you cannot prevent all fevers, good hygiene practices such as regular handwashing, keeping vaccinations up to date, teaching children not to share utensils or cups, and avoiding contact with sick individuals can reduce the frequency of infections that cause fever.

Since fever is the body's natural response to infection, preventing fever means preventing the infections that cause it. While children inevitably catch viruses and other illnesses, especially during their early years in daycare or school, several strategies can reduce the frequency and severity of infections. These preventive measures benefit the whole family and help maintain overall health.

Hand hygiene is the single most effective way to prevent the spread of many infections. Teach children to wash hands thoroughly with soap and water for at least 20 seconds, particularly before eating, after using the toilet, and after coming home from school or public places. When soap and water are not available, alcohol-based hand sanitizers containing at least 60% alcohol are an effective alternative. Model good hand hygiene yourself, as children learn by watching parents.

Keeping immunizations up to date protects children from many serious infections that cause fever. While vaccines may occasionally cause mild fever as a side effect, this temporary reaction prevents potentially severe illnesses. The recommended vaccination schedule is designed to provide protection when children are most vulnerable to specific diseases. Discuss any concerns about vaccines with your healthcare provider, who can provide evidence-based information about benefits and risks.

Teaching children not to share cups, utensils, or water bottles helps prevent transmission of viruses that spread through saliva. Encouraging children to cover coughs and sneezes with their elbow rather than hands reduces droplet spread. Keeping sick children home from school or daycare prevents spreading illness to others and allows the sick child to rest and recover.

Frequently Asked Questions About Fever in Children