Fever is a common symptom in children and is usually not a cause for concern if the general condition is otherwise good. As the most important goal, the cause of the fever must first be clarified. Medication to reduce fever should be based primarily on the child’s general condition, not on temperature.
Fever in children is one of the most common reasons parents seek medical advice. High fever always causes concern and uncertainty even among professionals. Fever is not a disease, but only a symptom that can even have a positive effect on the body’s defense against infections. Thus, whether and how fever should be treated depends less on the level of the temperature than on the cause of the fever and the child’s general condition.
Physiology of temperature regulation
Human body temperature varies between 35.6 and 37.5°C depending on age, time of day and physical activity. Although fever is a common symptom, there is no universal definition of the temperature at which one speaks of fever. However, 38 or 38.5°C is usually set as the limit.
Pathogenetically, fever results from a cytokine-mediated adjustment of the endogenous temperature set point in the hypothalamus: peripherally released interleukins, interferon, and tumor necrosis factor lead to an increase in prostaglandin synthesis (especially PGE2) in the hypothalamus, as a result of which body temperature rises until the new target value is reached. This increase in temperature is achieved by freezing (muscle tremors to shivering, etc.), decreased skin blood flow and increased metabolic activity. It is debated whether the frequently observed fever-associated fatigue can be explained by the increased IL-1 levels and the muscle and limb pain by the increased PGE2 levels. Mild tachycardia with fever is normal [1].
Body temperature measurement
Rectal temperature is usually considered the gold standard of temperature measurement. While this measurement is easy to perform and most reliable in infants, older children often find it very uncomfortable. In practice, in my opinion, the exact level of the temperature does not play such a decisive role that it is necessary to insist on rectal measurement. I make my therapy decision based on factors other than the exact level of temperature. It is nevertheless advisable to ask the parents about the temperature they have taken, because the subjective perception of what constitutes a fever varies greatly: anxious parents often interpret even temperatures below 39°C as worrying and state anamnestically that the child had a “high fever”.
Clarify the cause of the fever
Especially in childhood, fever is a very common and typical symptom. In most cases, it is actually a harmless accompanying symptom of infectious diseases that rarely actually requires treatment. Whether this is the case depends on the cause and possibly concomitant diseases. In the medical care of febrile children, differential diagnosis of the cause of fever is of central importance. If the underlying disease can be treated, the body temperature also returns to normal in almost all cases. In the case of a new onset of fever, it is important to find out whether the underlying cause is a viral infection, a bacterial infection or other rare causes. However, there is little correlation between the level and duration of fever and the severity or risk of complications of the disease.
As a rule, fever itself is not dangerous and fever retention does not lower the morbidity of a disease. On the contrary, there are indications that the immune system actually functions better with moderate fever (up to 40°C), i.e. that fever also has a physiological function. Exceptions to this rule are constellations in which the increased metabolism in the context of fever puts too much additional strain on the cardiopulmonary system. The increased metabolism reaches a critical limit much faster in the absence of reserves. This may be the case in acute shock or in certain rare underlying diseases such as metabolic disorders, traumatic brain injury, or cardiopulmonary disease. Disturbances of the water and electrolyte balance or severe feeling of illness with severe malaise may also require symptomatic therapy [2].
In certain situations with a high risk of serious infections, rapid and comprehensive evaluation and generous and early treatment are required, such as in children with neutropenia, HIV infection, or infants in the first three months of life.
The following comments refer to the frequent fever in the group of previously healthy children without significant preexisting underlying diseases [3].
Fever without focus
From the physician’s point of view, fever without focus is actually the most worrisome constellation because one should not overlook a severe, invasive bacterial infection and/or sepsis that can be treated with antibiotics, and the differentiation between bacterial and viral etiology is therapeutically crucial. In terms of differential diagnosis, a distinction should therefore be made between
- a viral infection that (with the exception of a herpes simplex infection) is treated only symptomatically,
- a severe invasive bacterial infection up to sepsis and
- a focal bacterial infection (especially meningitis, pneumonia or urinary tract infection)
take place.
Since urinary tract infection is the second most common cause of fever without focus after viral infections, especially in infants (but also at all ages), proper urinalysis is an essential part of clinical evaluation. A bag urine is only usable in case of an inconspicuous result, because there are many false-positive but hardly any false-negative results. If, on the other hand, the urine from the bag is conspicuous, new urine must be collected again in as sterile a manner as possible (sterile collection of midstream urine, bladder catheterization or suprapubic puncture) and carefully examined.
Overall, occult bacteremia or incipient sepsis are very rare, and the incidence of meningitis due to Haemophilus influenzae type B, pneumococcus, and meningococcus type C has also declined significantly since the introduction of vaccination. A seriously ill child in poor general condition should still be admitted as an inpatient for observation. Clearly, neonates or children in the first three months of life are at the highest risk, so they should be monitored very generously as inpatients [4,5]. In case of acute worsening or newly occurring additional symptoms, a calculated antibiotic therapy can then be initiated quickly, if necessary.
With the exception of urinalysis, laboratory tests are not mandatory. Determination of CRP and blood count may support clinical judgment but are not conclusive one way or the other. Some viral illnesses may also be associated with elevated CRP; conversely, a low CRP does not rule out bacterial infection if the course of illness is short (less than twelve hours). If the patient is in good general condition and there are no previous diseases or risk factors, an outpatient observation with follow-up the next day can be arranged [4].
Therapy depending on the general condition of the child
For otherwise healthy children, fever does not usually pose an additional health risk. It does not negatively affect the course or outcome of a disease. Therefore, the primary goal of therapy cannot simply be to lower the body temperature to normal values. Fever-reducing therapy is indicated only if it improves the child’s well-being. For values below 38.5°C, antipyretic therapy is indicated only in rare exceptional cases.
Also, the risk for the occurrence of febrile convulsions (a common fear of parents, especially if a febrile convulsion has already occurred) cannot be reduced by prophylactic administration of antipyretics, so this is not an indication for fever-reducing medication. Good parental education, on the other hand, is central.
Often, neither specific diagnosis nor therapy is necessary. As long as the child drinks and plays, the normal healing of an infection can be waited for. Further clarification is only necessary if the child’s condition deteriorates significantly or if the child no longer absorbs sufficient fluids.
Measures to reduce fever can be useful if the elevated body temperature is accompanied by severe physical discomfort or a feeling of illness, if there are disturbances in the water and salt balance, or if the child suffers from a serious underlying illness. Accompanying supportive therapy with the supply of sufficient fluids is important, since on the one hand the fluid requirement is increased in fever, and on the other hand dehydration itself can be the cause of increased temperature (“thirst fever”) [2].
Medication
Paracetamol and ibuprofen are the main drugs used to reduce fever in children. They can be evaluated as safe due to the long experience. Although other drugs such as metamizole or steroids are also effective, they are reserved for exceptional cases due to their spectrum of side effects. Acetylsalicylic acid (ASA) should not be used because of the risk of Reye syndrome, despite its high efficacy [6].
Fever is still one of the conditions most feared by parents because it is associated with severe illness, brain damage, seizures and death. De facto, the toxicity of antipyretic drugs (especially in the case of dosing errors) is actually the more relevant problem [7]. The frequently still recommended alternating use of paracetamol and ibuprofen has therefore been discouraged for some time, even if this can lower the temperature somewhat better: On the one hand, because dosing errors or overdoses occur more frequently, and on the other hand, because this is associated with a potentially higher toxicity – without any relevant improvement in the child’s condition [8]. In addition, this recommendation could encourage general “fever phobia”.
Paracetamol
Paracetamol is very suitable for reducing fever and, when dosed correctly, has hardly any side effects (however, in the case of overdosage or pre-existing liver dysfunction, severe poisoning with liver failure can occur). Recommended dosage is 10-15 mg/kg/dose maximum every four to six hours. Per day, a total dose of 75(-90 mg/kg body weight if treatment duration is less than three days) should not be exceeded. A measurable antipyretic effect occurs after about 30-60 minutes, reaches its maximum after about three hours, and lasts for four to six hours.
Ibuprofen
Ibuprofen has an anti-inflammatory effect in addition to its antipyretic effect. However, because it can impair kidney function, it should not be used at all in children under six months of age. Personally, I use it cautiously even in older children for toxicological or nephroprotective reasons and rather recommend paracetamol for primary antipyresis. However, if an antiphlogistic effect is also desired, e.g., in otitis media, ibuprofen appears to have a slight advantage. In addition, many parents like to give it in the form of Algifor® because most children like the taste and therefore take it willingly. The recommended dosage is 7.5-10 mg/kgKG/dose maximum every six to eight hours. The effect starts within the first hour after ingestion, reaches its maximum after three to four hours and lasts for about six to eight hours [1,6].
Take-Home Messages
- Fever is a common symptom in children and is not a cause for concern if the general condition is otherwise good.
- As the most important goal, the cause of the fever must first be clarified in order to be able to initiate treatment of the underlying disease, if necessary.
- Medication to reduce fever is only symptomatic treatment and should be based primarily on the child’s general condition, not on temperature.
- In children under six months of age, only paracetamol should be used; in older children, ibuprofen can also be used, but alternating administration is no longer recommended.
- In cases of fever without focus, proper urinalysis should always be performed to rule out urinary tract infection.
Literature:
- Ward MA, Edwards MS, Torchia MM: Fever in infants and childran: pathophysiology and management. Uptodate.com 2017 May 17.
- Kowalzik F, Zepp F: The febrile child – basics of treatment. Monatschr Kinderheilkd 2013; 161: 196-203.
- Kayman H: Management of Fever: making evidence-based decisions. Clin Pediatr (Phila) 2003; 42(5): 383-392.
- Huppertz HI: Fever without focus. Monatsschr Kinderheilkd 2013; 161: 204-210.
- Huppler AR, Eickhoff JC, Wald ER: Performance of low-risk criteria in the evaluation of young infants with fever: review of the literature. Pediatrics 2010; 125: 228-233.
- Sullivan JE, Farrar HC: Fever and antipyretic use in children. Pediatrics 2011; 127(3): 580-587.
- Sherman JM, Sood SK: Current challenges in the diagnosis and management of fever. Curr Opin Pediatr 2012; 24(3): 400-406.
- Wong T, et al: Combined and alternating paracetamol and ibuprofen therapy for febrile children. Cochrane Database Syst Rev 2013; (10): CD009572.
HAUSARZT PRAXIS 2017; 12(8): 12-14
