Fever in infants and children – children’s health problems – msd manual edition for patients

Fever in infants and children - children's health problems - msd manual edition for patients

Fever in infants and children

Deborah M. Consolini

, MD, Sidney Kimmel Medical College of Thomas Jefferson University

Normal body temperature varies from person to person and throughout the day (usually the highest in the afternoon). The normal body temperature is higher in preschool children. The temperature is highest between the ages of 18 and 24 months. Despite these fluctuations, most doctors define a temperature of around 38 ° C as a fever. The temperature can also be higher if it is measured rectally (see temperature measurement in children).

Although parents are often worried about the temperature of the child, the level of the fever does not necessarily indicate how serious the cause is. Some mild illnesses cause a high fever and some serious illnesses only cause a mild fever. Symptoms other than temperature (e.g. difficulty breathing, confusion, refusal of the chest or bottle) are a better indicator of the severity of a disease. However, a temperature above 41 ° C can be very dangerous in itself, although this rarely occurs.

Fever helps the body fight infection. Some experts believe that lowering the fever causes a disease to take longer or interfere with the immune system’s response. Therefore, although a fever is uncomfortable, it is not always necessary to treat a fever in otherwise healthy children. In children with lung, heart or brain disease, however, fever can cause problems because the fever puts a strain on the body (e.g. by increasing the heart rate). In such children, it is therefore important to lower the temperature.

Infants with a fever are generally irritable and sleep and drink poorly. Older children lose interest in playing. Usually the child becomes more irritable and less interested the higher the fever rises. However, sometimes children with high fever look amazingly healthy. Seizures can occur in children if their temperature rises or falls rapidly (called febrile seizures). Rarely does a fever rise so high that a child becomes listless, sleepy and unresponsive.

Temperature measurement in the child

The temperature can be measured in the anus, ear, mouth, forehead and under the armpit. It can be measured with a digital thermometer. Digital thermometers are easier to use and display the measured value much faster (usually they give a signal when the measurement is finished). Glass thermometers that contain mercury are not recommended as they can break and people could come into contact with the mercury.

Rectal temperature measurements are most accurate. They come closest to the child’s actual core body temperature. A lubricant should be applied to the thermometer tip for rectal temperature measurement. Then the thermometer is gently inserted approximately 1.25 to 2.5 centimeters into the rectum, the child lies face down. The child should be prevented from moving.

The ear temperature is measured using a special digital ear thermometer that measures the infrared radiation emitted by the eardrum. Ear thermometers are not very reliable in infants under 3 months. With an ear thermometer, the temperature probe is held at the entrance to the ear canal so that a seal is created. Then the start button is pressed. The temperature is shown on a digital display.

Oral temperatures are determined by placing a digital thermometer under the child’s tongue. Oral temperatures are reliable, but measurement is problematic in young children. It is difficult for small children to keep their mouths sealed around the thermometer long enough, which is necessary for a correct measurement. The age at which oral temperatures can be measured reliably varies from child to child, but is usually possible from the age of 4 years.

The Forehead temperature (temple temperature) is determined with a digital device that measures the infrared radiation emanating from the artery on the forehead (temporal artery). To determine the forehead temperature, the measurement button is pressed and the head of the thermometer is moved slightly from hairline to hairline over the forehead. The temperature is shown on a digital display. Forehead temperatures are not as accurate as rectal temperatures, especially in infants under 3 months.

Under armpit temperatures are measured by placing a digital thermometer directly on the skin in the child’s armpit. Doctors rarely use this method because it is less accurate than others (measurements are usually lower and vary widely). However, if caregivers do not want to measure the temperature rectally and do not have a device to measure the temperature in the ear or forehead, the measurement in the armpit is still better than measuring no temperature at all.


Fever occurs in response to infection, injury, or inflammation and can have many causes. Possible reasons for a fever depend on whether it lasts 14 days or shorter (acute) or longer than 14 days (chronic), and it also depends on the age of the child. Fever is usually acute.

Acute fever

Acute fever in infants and children is usually caused by infection. Teething can cause fever, but it usually does not rise above 38.3 ° C.

The common causes of acute fever are

Upper respiratory tract infections due to a virus, e.g. B. Colds or flu

Gastroenteritis (infection of the digestive tract) due to a virus

Certain bacterial infections, especially ear infections (otitis media), sinuses, pneumonia (pneumonia) and urinary tract infections

Newborns and young infants are at higher risk of certain serious infections because their immune systems are not yet fully developed. Such infections can contract before or during childbirth and can be associated with sepsis (serious infection of the blood), pneumonia (infection of the small alveoli) or meningitis (infection of the tissues surrounding the brain).

Children under 3 years of age who develop a fever (especially when the temperature rises to 39 ° C or more) sometimes have bacteria in the blood (bacteremia). Unlike older children, they sometimes suffer from bacteremia without showing any symptoms other than fever (referred to as occult bacteremia). Today, vaccinations against the bacteria (Streptococcus pneumoniae and vaccine against Haemophilus influenzae type B">Haemophilus influenzae type B [HiB]), which normally cause occult bacteremia. Therefore, the use of these vaccines has practically eliminated occult bacteremia in children of this age group.

Among the less common causes Acute fever includes side effects from vaccinations and certain medications, bacterial infections of the skin (cellulitis) or joints (septic arthritis), encephalitis, and viral or bacterial infections of the brain (Kawasaki syndrome) and meningitis (meningitis) or both. A heat stroke causes a very high body temperature.

Typically, a fever caused by vaccination lasts for a few hours to a day. However, some vaccinations can cause a fever of 1 or even 2 weeks in duration (e.g. vaccination against measles). Children who have a fever at the time of a planned vaccination can still be vaccinated if they have low fever and no other serious illness.

Chronic fever

Chronic fever is mostly caused by

A prolonged viral disease

Successive viral diseases, especially in young children

Chronic fever can also be caused by many other infectious and non-infectious diseases.

Infectious causes of chronic fever include:

Infection of the digestive tract by bacteria or parasites

Inflammation of the heart (such as endocarditis)

Non-infectious causes of chronic fever include:

Juvenile idiopathic arthritis or other connective tissue disorders

Occasionally children or those caring for the child pretend to have a fever. Sometimes the cause cannot be determined.


Detecting a fever is not difficult. Finding the cause of the fever can be difficult.

Warning signals

Certain symptoms are cause for concern. These include

Any fever in infants younger than 2 months

Listlessness or listlessness

Bleeding in the skin, recognizable as tiny reddish-purple spots (petechiae) or small spots (purpura)

Continuous crying in an infant or toddler (heartbroken)

Headache, stiff neck, confusion, or a combination of these in an older child

When to consult a doctor:

Children with fever should be examined immediately by a doctor if they can see any of the warning signs or if they are less than 2 months old.

Children who have no warning signs and who are between 3 months and 3 years old should be examined by a doctor if the fever rises to 39 ° C or higher, if there is no obvious upper respiratory infection (ie the children sneeze and have a runny or stuffy nose) or if the fever persists for more than 5 days.

In children who have no warning signs and who are older than 3 years, the urgency of a medical examination depends on the symptoms of the child. Children who have upper respiratory symptoms but appear otherwise healthy may not need further examination. Children who are older than 3 years and whose fever persists for more than 5 days should be examined by a doctor.

What the doctor does:

Doctors first ask questions about the child’s symptoms and medical history. Then they perform a physical exam. By describing the child’s symptoms and a thorough examination, the doctor is usually able to find out the cause of the fever (see table: Some causes and characteristics of fever in children).

The doctor measures the child’s temperature. For an accurate temperature, this is measured rectally in infants and young children. The breathing rate is recorded. When the child appears sick, blood pressure is measured. If the child coughs or has breathing problems, a sensor is attached to a finger or earlobe to measure the oxygen concentration in the blood (pulse oximetry).

In the course of the examination, the doctor pays attention to warning signals (e.g. ill appearance, listlessness, listlessness and inconsolability) and especially how the child reacts to the examination, e.g. B. whether the child is listless and passive or extremely irritable.

Occasionally the fever itself can cause warning signals in the child, e.g. B. listlessness, listlessness and a sick appearance. The doctor can give the child antipyretic medication (e.g. ibuprofen) and examine it again if the fever has dropped. It is comforting when a listless child becomes active again after lowering the fever and wants to play. On the other hand, it is worrying if a child who appears ill continues to appear ill even though the temperature is normal.

Some causes and characteristics of fever in children

Acute fever (up to 14 days)

Upper respiratory tract infection due to a virus

Runny or stuffy nose

Usually a sore throat and cough

Sometimes swollen lymph nodes on the neck without redness and tenderness

Other infections due to a virus

No symptoms other than fever in some infants or children

Possibly recent contact with infected people or certain animals, or ingestion of contaminated food or water

Sometimes physical exams and tests with the stool

Pain in one ear (difficult to see in infants and young children who do not speak)

Sometimes rubbing or pulling on the ear

Red, swollen throat

Pain when swallowing

Sometimes a cervical smear with culture or a quick streptococcal test (both done with a sample obtained from the back of the throat with a cotton swab)

In children under 3 years

No other symptoms

Cough and rapid breathing

Often shortness of breath or chest pain, or both

Usually a chest x-ray

Red, painful, slightly swollen skin area

Painful urination

Sometimes blood in the urine

Vomiting and loss of appetite in infants

Encephalitis (a rare infection of the brain)

Baby: Sometimes protrusion of the soft areas (fontanelle) between the skull bones, indolence (apathy) or inconsolability

Older children: Headache, confusion or listlessness

Newborn: Protrusion of the soft areas (fontanelle) between the skull bones, inconsolability, loss of appetite and / or listlessness

Baby: Teasiness and irritability (especially when on the arm), inconsolability, loss of appetite and / or listlessness

Older children: Headache, sensitivity to light, listlessness, vomiting and / or stiff neck, which makes it difficult to put the chin on the chest

Recent vaccinations

Recent addition of a new drug

Fever for more than 5 days

Red eyes, lips and tongue

Painful swelling of the hands and feet

Sometimes swollen lymph nodes on the neck

EKG and echocardiography

Sometimes urine tests, abdominal ultrasound, or an eye exam

Swollen painful joints

New heart murmur, recognized by a medical examination

Sometimes rash or nodules under the skin

Sometimes jerky, uncontrollable movements or changes in behavior

Frequent history of streptococcal throat

Creation of a throat culture

EKG and echocardiography

Chronic fever (lasting more than 14 days)

Infections due to a virus, e.g. B.

Prolonged weakness and fatigue

Sometimes swollen lymph nodes on the neck, sore throat, or both

Sometimes yellowing of the eyes (jaundice)

Intermittent headache, runny and stuffy nose

CT of the sinuses

Abdominal pain and often tenderness when touched

Abdominal CT (abdomen)

Swollen, red, painful joint

Examination of synovial fluid that is removed from the joint with a needle

Pain in the affected bone

Sometimes a skin infection near the affected bone

CT or MRI scan of the bone, or both

Sometimes bone biopsy to detect bacteria (culture)

Sometimes a heart murmur

Blood tests for bacteria (blood culture)

Weight loss or poor weight gain

Chest x-ray

Possibly culture of a sputum sample and / or blood tests

Malaria (depending on geographic location)

Chills followed by a fever that can rise above 40 ° C

Fatigue and indefinable complaints (feeling unwell), headaches, body aches and nausea

Sometimes headache and neck pain

Sometimes swollen, painful joints (e.g. knees)

Sometimes blushing in one or more places

Occasionally known history of a tick bite

Frequently swollen painful lymph nodes

Sometimes a bump on the skin where the cat scratched

Blood in the stool, cramping abdominal pain, weight loss and loss of appetite

Sometimes arthritis, rashes, mouth sores, and tears in the rectum

Sometimes CT or X-rays after inserting barium into the rectum (barium enema)

Joint and connective tissue diseases, e.g. B.

Swollen, red, painful joints

Poor weight gain or loss and loss of appetite

Collection (aspiration) of a bone marrow sample for examination

Sometimes bone scintigraphy and / or MRI scan of the bone

Sometimes chest or abdomen CT

Periodic fever syndromes, e.g. B.

Periodic fever with stomatitis aphtosa, pharyngitis, sore throat and adenitis (PFAPA syndrome)

Fever that recurs in frequently predictable cycles, with healthy phases in between

Sometimes mouth sores, sore throat and swollen lymph nodes

Sometimes chest and abdominal pain

Sometimes family members had similar symptoms or were diagnosed with one of the familial periodic fever syndromes

Medical examination during a fever episode

Blood tests during and between the fever episodes

Sometimes genetic tests

Usually misjudgment of normal body temperature fluctuations or over-interpretation of common small viral diseases

Usually no other worrying symptoms

Thorough and exact record of diseases and temperatures, as well as a description of the general condition of the child and family

Occasional blood tests to rule out other causes and to reassure the parents

* The characteristics include symptoms and findings from the medical examination. The characteristics mentioned are typical, but do not always occur. Diseases that cause chronic fever also cause fever in the first 7 to 10 days of fever.

CT = computed tomography; EKG = electrocardiogram; MRI = magnetic resonance imaging.


at acute fever the doctor can often make a diagnosis without tests. For example, if children do not appear to be very sick, the cause is usually a viral infection; if you have a runny nose, wheezing or cough, there is a respiratory infection, and if you have diarrhea and vomit, it is usually due to gastroenteritis. In such children, the diagnosis is clear and no further tests are required. Even if no specific symptoms indicate a diagnosis, the cause in children who otherwise do not appear to be very sick is usually a virus infection. Doctors only try other children who may have a more serious illness. The possibility of serious illness (and consequently necessary tests) depends on the age, symptoms and overall appearance of the child and the individual illness that the doctor suspects (see table: Some causes and characteristics of fever in children).

If newborn (28 days old or younger) have a fever, they are admitted to the hospital for further tests because the risk of a serious infection is high. The tests usually include blood and urine tests, a spinal puncture (lumbar puncture) and sometimes an X-ray of the chest.

at Infants aged between 1 and 3 months blood and urine tests (urine analysis) are carried out and cultures are established. Whether or not a child is admitted to the hospital and a chest x-ray and spinal puncture depends on the results of the blood and urine tests. The appearance of the baby also plays a role, as does the question of whether a follow-up examination can be carried out. In babies under 3 months of age, tests are done to look for bacteremia, urinary tract infections and meningitis (meningitis). The tests are necessary because the cause of the fever is difficult to determine in infants and because they are at high risk of serious infection due to their immature immune system.

If Children who are between 3 months and 3 years old, Look healthy and can be carefully monitored, no tests are required. If the symptoms indicate a specific infection, the doctor will perform the appropriate tests. If children do not have symptoms that indicate a specific illness, but still have a temperature of 39 ° C or more, blood and urine tests are usually done. Whether a child is admitted to the hospital depends on the appearance of the baby and whether a follow-up examination can be carried out.

at Children older than 3 years, tests are usually not performed unless the children have specific symptoms that indicate a serious illness.

at chronic fever tests are often carried out. If the doctor suspects a particular condition, tests for that condition are performed. If the cause is unclear, screening tests are performed. Screening tests include a large blood count, urine analysis and culture, and blood tests to check inflammation parameters. Inflammation parameter tests include blood cell sedimentation rate (ESR) and CRP (C-reactive protein) level measurement. Sometimes doctors do other tests when there is no clear cause, including stool tests, tuberculosis tests, chest chest x-ray, and computer tomography (CT) of the sinuses.

Seldom does the fever persist and doctors cannot identify a cause even after extensive tests. This type of fever is known as fever with no known cause. Children with a fever of unknown origin are much less likely to have a serious illness than adults.


If the fever is caused by an illness, the illness is treated. Other fever treatments focus on making children feel better.

General measures

In order for children with fever to feel better without taking medication, there are the following options:

Provide the child with sufficient fluids to prevent dehydration

Place cool, damp cloths (compresses) on the forehead, wrists and calves

Put the child in a warm bath (only slightly colder than the child’s temperature)

Since the child’s temperature may increase due to tremors, methods that could cause tremors, e.g. B. Take off and cold baths, only to be used at dangerously high temperatures of 41 ° C and above.

The child should not be rubbed with alcohol or witch hazel extracts, as the alcohol can be absorbed through the skin and cause damage. There are many useless home remedies that range from harmless (e.g. putting onions or potatoes in the child’s socks) to unpleasant (e.g. cupping).

Antipyretic drugs

Fever in an otherwise healthy child does not necessarily need to be treated. However, so-called antipyretic drugs can help the child feel better by lowering the temperature. These medications have no effect on an infection or other condition that causes the fever. However, if the child has a heart, lung, brain, or nerve disorder, or has had febrile seizures in the past, the medication may be necessary to reduce the additional stress that the fever places on the body.

The following drugs are usually used:

Acetaminophen, administered orally or by suppository

Ibuprofen, administered orally

Acetaminophen is mostly preferred. Ibuprofen can irritate the stomach wall with long-term use. These drugs are available without a prescription. The recommended dosage is given on the package insert, but can also be prescribed by the doctor. It is important to administer the correct dose at the correct intervals. These drugs do not work if too little of the drug or if it is given too rarely. Although these drugs are relatively safe, over or over-administration of the drug can lead to an overdose.

Acetaminophen or ibuprofen is rarely given to prevent a fever, e.g. B. when vaccinating infants.

Aspirin is no longer used to lower fever in children because it can interact with certain viral infections (e.g. flu or chickenpox) and can cause a serious condition called Reye’s syndrome.

Most important points

A fever is usually caused by a viral infection.

The cause of a fever and whether tests need to be carried out depend on the child’s age.

Infants who are younger than 2 months and have a temperature of approx. 38 ° C or more must be examined by a doctor.

If children aged 3 months to 3 years with fever have no symptoms that indicate a specific disease, but still have a temperature of 39 ° C or more, they must be examined by the doctor.

Teething does not cause a high fever.

Medications that lower the fever can contribute to the well-being of the child, but have no effect on the disease that causes the fever.

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