CME -- Fever: Measuring and managing a sizzling symptom


The authors separate fever fact from fever fiction, review which thermometers should be used in which patients, and discuss safe and appropriate use of antipyretics and sponge bathing.


Fever: Measuring and managing a sizzling symptom

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Choose article section...LEARNING OBJECTIVES Fear of fever Diagnosing fever by touch Thermometers: Which, when, why? The optimal site for measuring temperature Antipyretics: Cautionary notes Alternate dosing Sponge bathing: Helpful or harmful? Fever in perspective

By Molly E. Rideout, MD, and Lewis R. First, MD

Fever has been around for eons but it continues to produce fear in many parents and anxiety in many health-care providers. Here we separate fever fact from fever fiction, review which thermometers should be used in which patients, and discuss safe and appropriate use of antipyretics and sponge bathing.

The role of body temperature in health and disease has been debated for centuries. Mammals, birds, reptiles, fish, and even insects have an innate ability to mount a febrile response. It has been postulated that the very survival of a species depends on fever. Teleologically, fever works to protect its host from mild or moderate disease and infection. In a severe infection, though, fever may expedite the host's demise, thus protecting the species from an epidemic.1 From a public health perspective, this is logical, but recognizing the protective role of fever is usually of little comfort to the parents of a sick, febrile child.



After reviewing this article the physician should be able to:


Many studies have demonstrated the beneficial effect of fever on an affected person.1-3 Fever inhibits the growth of certain viruses and bacteria.2 Varicella lesions take slightly longer to crust over if antipyretics are used.3 Malarial-induced fever was initially used as a treatment for neurosyphilis.1 Artificially-induced fever was also an early treatment for gonorrhea,2 and it is now being used experimentally to treat certain tumors.

If fever is an evolutionary advantage in mild or moderate infections, why is so much energy devoted to reducing it? And, to answer that with another question, why are so many people afraid of fever?

Fear of fever

So-called fever phobia reflects a fear of fever alone as a disease process. The landmark study on fever phobia by Schmitt in 1980 was based on a survey of 81 patients attending an inner-city clinic.4 It revealed that 18% of parents of patients in this study—representing all socioeconomic classes— believed that permanent harm, especially brain damage, could result from a fever above 102º F. A full 52% believed that death or neurologic devastation could occur if their child's temperature climbed above 104º F. And 56% of parents reported giving an antipyretic for a temperature between 98.6º F and 100º F, which probably doesn't represent true fever. (See "What is normal body temperature?" below; for conversions of Fahrenheit to Celsius, see Table 1.)


Temperature equivalents

Fahrenheit converted to...


Because most parents surveyed about fever say that they base their home regimen on what they are taught by personnel in physicians' offices, either in person or on the telephone, it is imperative that we give a clear and consistent message about fever management. Unfortunately, physicians and nurses also may have "fever anxiety," and, consequently, may send mixed messages to parents about the damage that fever can cause. In a survey of 151 Massachusetts pediatricians, for example, 65% believed that fever alone could be dangerous.5 The majority (58%) of these pediatricians believed that a fever above 104° F in an otherwise healthy child could cause a seizure, while 23% believed that dehydration could result and 10% believed brain damage could occur.

It is true that fever may lower the seizure threshold in a person otherwise predisposed to seizures, but by itself fever is not the cause. Brain damage or death from fever alone is unlikely except in the case of environmentally-induced fever—hyperthermia resulting from being left in a closed car in hot weather, for example. Fever may indeed lead to dehydration if associated with decreased fluid intake or loss of fluids from vomiting and diarrhea. Dehydration is unlikely to result from fever alone, however.

Diagnosing fever by touch

Controversy has persisted for more than a century about when to measure temperature, at which site, and with which type of thermometer. In the real world, most parents take their child's temperature at the first sign of a fever. They often begin the diagnostic detection of fever by touching the child's skin. A caregiver's touch is highly reliable when fever is absent. But touch is unreliable when fever is present.6 The sensitivity of a caregiver's subjective assessment of fever ranges from 74% to 89%, with a positive predictive value (proportion who correctly report fever) as low as 22% and a negative predictive value (proportion who correctly report absence of fever) as high as 99%.6

A false impression of fever may be caused by vasodilation from relative hyperthermia rather than from fever itself. This fact underscores the importance of educating parents about fever and of confirming measurement with a thermometer when fever is believed present on the basis of palpation and when documentation of that fever will make a diagnostic or therapeutic difference. The latter applies in only a few instances—for example, to infants under 3 months of age, to immunocompromised children, and to children who have had a previous febrile seizure. In such cases, the precise temperature will affect management decisions— such as who warrants an evaluation for sepsis and empiric treatment with antibiotics and whether a child should receive aggressive treatment with antipyretics. That being said, even in these instances the patient's appearance and history can be just as, if not more, critical than temperature.

Thermometers: Which, when, why?

Many types of thermometers have been developed and marketed to consumers and physicians over the past 15 years. Glass mercury, digital, pacifier, and ear-based thermometers are all available to parents, and clinicians need to be aware of the risks and benefits of each. (Table 2 lists examples of brands and retail prices.)


Thermometers: A sampling of products

Type/Manufacturer or brand name
Manufacturer’s suggested retail price*


Digital (oral, rectal, axillary)
$9.99–$10.75 $8.95 $9.89 $8.95 $9.99 $4.99

$44.88–$59.99 $63.99 $59.97–$79.95 $49–$69.95

Pacifier (supralingual)
$4.95 $5 $16 $9.99 $9.26 $9.83–$18.95 $8.98–$15.80 $8.99 $9.45–$13.49


Regrettably, although many studies have examined the sensitivity and specificity of various thermometry techniques, research on clinical outcomes in relation to the readings of each device is lacking. That being said, rectal temperature remains the gold standard against which the accuracy of thermometers is judged. One drawback to using rectal temperature as a standard for comparison is that rectal measurements lag behind rapid changes in core body temperature because a large muscle mass insulates the rectal area.7

Although a pulmonary artery temperature is probably the closest measurement of core body temperature, it is obviously not feasible to get a pulmonary artery reading in most children. Esophageal and bladder temperatures closely correlate with core body temperature as well, but they are also too invasive to be taken routinely.

Glass mercury thermometers have traditionally been the standard used in homes and physicians' offices and are used for comparison in many studies. Many parents are unable to read them, however. There have also been concerns about transmission of infection (rectally) and about breakage with resultant mercury exposure.8 In an effort to make thermometry easier and safer, new thermometer products, such as digital and ear-based thermometers, have been developed and studied.

Digital thermometers can be used to take the rectal, oral, or axillary temperature. There is no significant difference in readings between glass mercury and digital thermometers by either the oral or axillary route.9 It is extrapolated that rectal measurements also correlate well. Digital thermometers generally take 60 seconds to give a measurement; they use a "predictive" mode, in which they estimate the final temperature based on the rate of temperature change.

The oral temperature appears to correlate with core body temperatures if the patient is able to cooperate, which is usually the case by the age of 5 years.10 (Some children as young as 3 years old may be able to cooperate.) The oral temperature may be affected by consumption of hot or cold liquids, by tachypnea, or by mouth breathing. The thermometer should be inserted into the sublingual pouch approximately 2 to 4 cm to insure the most accurate measurement. Parents should monitor the child during the period of measurement because of the possibility that the child will try and falsify the reading—by holding the thermometer close to a light bulb, for example.

Many studies have shown that the axillary temperature has a poor sensitivity and a high variability.9,11 In one study of 30 children in a critical care setting, bladder temperature was compared with rectal, ear-based, and axillary temperatures. The correlation coefficients were approximately 95%, 85%, and 60%, respectively, even with a correction factor added to the axillary measurement.11 Although axillary temperature offers the advantage of patient comfort and little infection risk, it can vary greatly with environmental conditions and may not be reliable. Nonetheless, an elevated axillary temperature most likely represents a true fever, since axillary temperatures are consistently lower than rectal measurements.

Pacifier thermometers have become popular over the past five years and have been studied in children under 2 years. These devices consist of a nipple, which has a thermistor inside, and a detachable plastic handle. The supralingual temperature is an average of 0.5º F lower than the rectal temperature, so this amount must be added to the thermometer reading or the sensitivity is unacceptably low (72% without adding 0.5º F, vs. 92% when this amount is added).12 Instruct parents that, if the reading is in the febrile range after the 0.5º F has been added, they should take the child's temperature again rectally or orally.

Pacifier thermometers are impractical for the office because they take an average of three minutes and 23 seconds (and as long as four minutes and 15 seconds) for a reading. They are appropriate for the home if the temperature correction is made. It is doubtful, though, whether the device can be kept inside the mouth the necessary amount of time without popping out, making home accuracy questionable.

Tympanic membrane thermometers use an infrared beam to detect the amount of heat radiating from the tympanic membrane, which shares a common circulation with the hypothalamic thermostat. The ear probe is placed into the ear canal and pointed toward the opposite temple, giving a reading in less than three seconds.

Ear thermometers are fast and comfortable and are free of the risk of infection or injury. There is controversy, however, about their reliability. For one thing, the ear probe, designed for adults and therefore comparatively wide for children, makes pointing the infrared beam at the tympanic membrane of a young child difficult, potentially leading to false readings.

Several studies have shown a high degree of variability between the right and left ear.13-16 Measurements in the same ear are also highly variable.13 It has therefore been recommended that ear-based temperatures be taken in only one ear (generally the left, since most nurses are right-handed), and that more than one measurement be taken, using only the highest one. On the plus side, ear-based temperature readings do not seem to be affected by otitis media, cerumen, or crying.14,15,17

Most studies have demonstrated that a tympanic temperature is an average of 1.0º F to 1.8º F lower than a rectal temperature.14,18 In one study of 370 children age 6 months to 6 years, ear-based measurement had a sensitivity of 76% in detecting a fever >100.4º F and only 57% in detecting a high fever (>102.9º F).14 The majority of errors in this study represented underestimation of fever, as is true in most studies, but there were also a significant number of falsely elevated readings. Eight percent of children who were afebrile on rectal measurement were febrile with the ear-based thermometer, and 4% who had a low fever on rectal measurement (<102.9º F) had a high fever on ear-based measurement (>102.9º F). More studies need to be performed to establish normative data for ear-based thermometers in children.

Because hospital studies have documented the lack of reliability of tympanic membrane measurements by different care providers,18,19 it's possible that home use of ear-based thermometers by parents may produce inaccurate measurements. In addition, the different modes of ear-based thermometers, which use built-in calculations to convert measurements to rectal, oral, axillary, or "core" temperatures, can be confusing for parents. The offsets for these calculations vary by thermometer brand, making accurate measurement even more difficult. Furthermore, since the offsets were originally based on studies in adults,20 the meaning of these offsets for children—whose ear canals are shorter and possibly more vulnerable to environmental temperature changes—is uncertain.

Temporal artery thermometers have recently been developed that measure infrared radiation emissions through the skin over the temporal artery using a transducer that rolls across a child's forehead. In an initial study, sensitivity was only 65% for detecting fever higher than 100.4º F but 92% for detecting fever higher than 102.2º F.21 More research is needed on this type of thermometer before its use becomes widespread.

The optimal site for measuring temperature

Another important question facing parents and pediatricians alike is what body site should be used to measure temperature at different ages. In infants, rectal temperature remains the standard of care, especially in infants younger than 3 months. If parents of an older infant prefer to use the pacifier or axillary digital thermometer as an initial screen (remembering to add 0.5º F and 1.0º F, respectively), either of these two methods is acceptable, though neither is ideal; the limitations discussed previously need to be recognized.

In the toddler and preschool-age child, there are few reliable options for thermometry. Fortunately, it is rarely necessary to know the precise temperature of a patient this age. Ear-based thermometry may be the best option in a clinic setting, if all staff are trained in the technique. At home, rectal temperature should be the method of choice. Axillary or ear-based measurements are also acceptable, bearing in mind that both methods have a very low sensitivity.

Oral temperature can be highly reliable when a child is old enough to cooperate.

Antipyretics: Cautionary notes

If a thermometer indicates a fever in their child, parents often want to treat it, using an armamentarium of antipyretics to make the child more "comfortable." They frequently do so without seeking medical attention. Clinicians need to be aware of which over-the-counter medicines parents are choosing because there is a high risk of dosing errors and even accidental overdose.

Most parents give their children acetaminophen or ibuprofen. As antipyretics, these agents block prostaglandin synthesis and lower the hypothalamic set point. Other classes of drugs are also marketed as fever reducers. For example, "children's aspirin," despite its association with Reye syndrome, still sits next to children's acetaminophen on some store shelves, with dosing instructions for ages 2 and older on the label. (Because of the link to Reye syndrome, parents should be admonished not to give aspirin to their child.) Many cold and cough remedies also contain acetaminophen. Parents may not read the label carefully—or may not be able to read it. (Most labels on OTC medicines require at least an 8th grade reading level, and, nationwide, 20% of adults have a reading level of less than 5th grade.22) As a result, parents may accidentally give their child double or more the correct dosage of acetaminophen. Acetaminophen can be toxic even at a dosage less than twice the recommended level.23 What's more, certain OTC remedies contain alcohol, which can increase the risk of hepatic toxicity.

Several different formulations of acetaminophen and ibuprofen are available (Table 3). With acetaminophen, reported dosing errors have included giving infant drops (500 mg/5 mL) instead of the children's syrup (160 mg/5 mL), and giving adult tablets (325 mg) instead of children's chewables (80 mg, 160 mg). Similar mistakes have been made with ibuprofen in different formulations. In a retrospective study of 47 patients under 10 years who had acetaminophen-induced hepatotoxicity from multiple dosing, 52% had been given adult-strength tablets.24


Antipyretic formulations

Infant drops
Chewables, junior strength
Tablets junior strength

80 mg/0.8 mL (500 mg/5 mL)
160 mg/5 mL
80 mg
160 mg
80 mg (capsule sprinkles)
160 mg (capsule sprinkles)
80 mg,120 mg
80 mg (quick dissolve)
160 mg (quick dissolve)
80 mg/0.8 mL
160 mg/5 mL
80 mg
160 mg
120 mg

50 mg/1.25 mL
100 mg/5 mL
50 mg
100 mg
50 mg/1.25 mL
100 mg/5 mL
50 mg
100 mg
100 mg
50 mg/1.25 mL
100 mg/5 mL
50 mg/1.25 mL
100 mg/5 mL


Caregivers' mistakes may include not only incorrect dosing but also incorrect measuring. In a study examining OTC medications dispensed by caregivers, only 40% stated the appropriate dose for their child and only 67% accurately measured the dose they intended to give (accuracy was considered a measurement within 20% of the intended dose).25 Physicians and nurses need to recommend specific formulations and doses to parents to help prevent potentially fatal mistakes.

When acetaminophen and ibuprofen are used in equipotent doses —acetaminophen 15 mg/kg and ibuprofen 10 mg/kg—both are equally effective at reducing fever and equally well tolerated.26 Acetaminophen is dosed every four to six hours, with a maximum of five doses in a 24-hour period. Ibuprofen is dosed every six to eight hours. In a recent survey of 161 pediatricians,26 most said that acetaminophen (10 or 15 mg/kg a dose) or ibuprofen (7.5 or 10 mg/kg a dose) is their antipyretic of choice. Of those who said their selection of antipyretic was temperature-dependent, nearly half recommend ibuprofen rather than acetaminophen for a fever greater than 102º F. Almost a third of pediatricians admitted to using ibuprofen in infants younger than 6 months, although this is not an approved indication.

Alternate dosing

The idea of alternating antipyretics for more effective reduction of fever is not new. Before the association between Reye syndrome and aspirin became known, the practice of alternating aspirin and acetaminophen was commonly recommended, although not universally accepted.4 In the same survey of 161 pediatricians mentioned previously, 50% recommended alternating acetaminophen and ibuprofen,26 even though the efficacy and safety of this regimen has never been studied well. Seventy percent of pediatricians who responded to the survey had been out of residency training less than five years, and one can conjecture that they were swayed by parental anxiety about fever more than experienced physicians were.

Almost half (47%) of pediatricians who recommend an alternating regimen recommend giving acetaminophen every four hours and ibuprofen every six hours, even though acetaminophen every four hours surpasses the maximum daily dosage of this drug. Parents must be told that more than five doses in a 24-hour period exceeds the maximum daily dosage.26 Poison control centers receive many calls about confusing instructions given in regard to alternating antipyretics.27 Since the potential for errors is so great, the practice of alternating antipyretics should not be encouraged.

Sponge bathing: Helpful or harmful?

It is common practice for parents to use external cooling measures, such as tepid sponge bathing, on their febrile child. Such measures do not reset the hypothalamic set point. If they are used in conjunction with an antipyretic, however, they can, theoretically, help the body reach the new set point faster. A recent study showed that tepid sponging after antipyretic use reduced fever more rapidly over the first hour. Over two hours, however, no difference was noted in temperature reduction compared with what was observed in patients receiving an antipyretic alone.28 There was also more discomfort—crying, shivering, goose bumps—associated with sponging than in the control group.

If external cooling measures are used, they should always be used in conjunction with antipyretics. Sponging or other external cooling measures alone may actually cause temperature to rise, as the body uses shivering and vasoconstriction to try and reach the hypothalamic set point. External cooling measures should be abandoned if a child experiences discomfort.

Fever in perspective

As clinicians, we need to remember to use fever only as a diagnostic tool. Its importance relates to the underlying disorder that it represents, and not to fever as a harmful entity itself. In certain groups of patients, such as infants younger than 3 months and neutropenic patients, precise temperature measurement may influence the decision to evaluate for sepsis. More commonly, however, clinical judgment takes precedence over measurement of temperature.

We need to be aware of how parents react to and manage fever. Most parents surveyed say they use advice from the physician's office to guide management of fever,4 but many also turn to the World Wide Web for information. A Web search revealed 41 sites that offer advice about managing fever.29 Great variability exists across Web sources in such recommendations as how to take a temperature, what type of thermometer to use, and when and how to use tepid sponging. Clinicians need to be aware of the ease with which parents can obtain information from the Web—information that may be from unreliable sources.

We need to give careful and sound advice to parents about measuring temperatures and managing fever. Recommending frequent temperature-taking and aggressive attempts at fever reduction in an otherwise comfortable patient may only serve to heighten the fear of fever. When instructing parents on the use of antipyretics, we need to specify the formulation and dose to prevent dosing errors—and to keep our patients from really getting burned.


1. Blumenthal I: Fever—Concepts old and new. J R Soc Med 1997;90:391

2. Bass LW: Fever revisited. Arch Pediatr Adolesc Med 1997;151:647

3. Mackowiak PA: Fever: Blessing or curse? A unifying hypothesis. Ann Intern Med 1994;120:1037

4. Schmitt BD: Fever phobia: Misconceptions of parents about fevers. Am J Dis Child 1980;134:176

5. May A, Bauchner H: Fever phobia: The pediatrician's contribution. Pediatrics 1992;90(6):851

6. Kofoed PL, Dias F, Lopes F, et al: Diagnosis of fever in Africa. Lancet 1998;351:373

7. Loveys AA: Measuring temperatures. Pediatr Infect Dis J 1998;17:920

8. Shimoyama T, Kaneko T, Horie N, et al: Floor of mouth injury by mercury from a broken thermometer. J Oral Maxillofac Surg 1998;56:96

9. Shann F, Mackenzie A: Comparison of rectal, axillary, and forehead temperatures. Arch Pediatr Adolesc Med 1996;150:74

10. Dinarello CA, Bunn PA: Fever. Semin Oncol 1997;24(3):288

11. Erickson RS, Woo TM: Accuracy of infrared ear thermometry and traditional temperature methods in young children. Heart & Lung 1994;23:181

12. Press S, Quinn BJ: The pacifier thermometer: Comparison of supralingual with rectal temperatures in infants and young children. Arch Pediatr Adolesc Med 1997;151:551

13. Childs C, Harrison R, Hodkinson C, et al: Tympanic membrane temperature as a measure of core temperature. Arch Dis Child 1999;80:262

14. Brennan DF, Falk JL, Rothrock SG, et al: Reliability of infrared tympanic thermometry in the detection of rectal fever in children. Ann Emerg Med 1995;25(1):21

15. Modell JG, Katholi CR, Kumaramangalam SM, et al: Unreliability of the infrared tympanic thermometer in clinical practice: A comparative study with oral mercury and oral electronic thermometers. South Med J 1998; 91(7):649

16. Modell JG, Strong CA, Hagood L: Hope for the infrared tympanic thermometer: One model outperforms the others. South Med J 1999;92(7):737

17. Kahyaoglu O, Babka I, Demirci C, et al: Effect of crying on infrared tympanic temperature measurement in pediatrics. Clin Pediatr (Phila) 1997;36:487

18. Petersen MH, Hauge HN: Can training improve the results with infrared tympanic thermometers? Acta Anaesthesiol Scand 1997;41:1066

19. Amoateng-Adjepong Y, Del Mundo J, Manthous CA, et al: Accuracy of an infrared tympanic thermometer. Chest 1999;115(4):1002

20. Chamberlain JM, Terndrup TE, Alexander DT, et al: Determination of normal ear temperature with an infrared emission detection thermometer. Ann Emerg Med 1995;25(1):15

21. Greenes DS, Fleisher GR: Accuracy and tolerability of a noninvasive temporal artery thermometer for use in infants. Abstract. Pediatric Research April 2000;4(Pt 2): 108A

22. Heubi JE, Bien JP: Acetaminophen use in children: More is not better. J Pediatr 1997;130:175

23. Rivera-Penera T, Gugig R, Davis J, et al: Outcome of acetaminophen overdose in pediatric patients and factors contributing to hepatotoxicity. J Pediatr 1997; 130:300

24. Heubi JE, Barbacci MB, Zimmerman HJ, et al: Therapeutic misadventures with acetaminophen: Hepatoxicity after multiple doses in children, J Pediatr 1998;132:22

25. Simon HK, Weinkle DA: Over-the-counter medications. Do parents give what they intend to give? Arch Pediatr Adolesc Med 1997;151:654

26. Mayoral CE, Marino RV, Rosenfeld W, et al: Alternating antipyretics: Is this an alternative? Pediatrics 2000;105(5):1009

27. Mofenson HC, McFee R, Caraccio T, et al: Combined antipyretic therapy: Another potential source of chronic acetaminophen toxicity. J Pediatr 1998;133(5):712

28. Sharber J: The efficacy of tepid sponge bathing to reduce fever in young children. Am J Emerg Med 1997;15:188

29. Impicciatore P, Pandolfini C, Casella N, et al: Reliability of health information for the public on the World Wide Web: Systematic survey of advice on managing fever in children at home. BMJ 1997;314:1875

DR. RIDEOUT is Clinical Assistant Professor, Department of Pediatrics, University of Vermont College of Medicine, Burlington, Vt.
DR. FIRST is Professor and Chair, Department of Pediatrics, at the same institution.

What is normal body temperature?

In 1868, Wunderlich published an opus on clinical thermometry in which he outlined standards for measurement that are still used today.1 He measured axillary temperatures on more than 25,000 patients, using a 22 cm-long thermometer. With these data, he developed a standard of normative values, including a normal human body temperature of 98.6° F.

A relatively recent study of 691 healthy infants under 3 months of age in a well-baby clinic demonstrated a mean rectal temperature of 99.4° F +/- 0.5° F.2 Using a definition of "fever" as two standard deviations above the mean, the study suggested that fever in newborns from birth to 1 month, 1 to 2 months, and 2 to 3 months is 100.4° F, 100.5° F, and 100.7° F, respectively. Little if any data exist in older infants and children, but 98.6° F is often considered the mean normal oral temperature and 99.3° F the mean normal rectal temperature for children older than 24 months. Many texts define fever as any temperature above 98.6° F,3 although normal temperature may actually range from 97° F to 100° F.4

Human temperature rarely exceeds 106° F without an external heat source.5 That is because there is a closely regulated thermostat mechanism in the anterior hypothalamus. The difference between hyperthermia and fever is explained by the difference in hypothalamic set point. In fever, the set point is higher than normal as a result of the release of cytokines, which influence the hypothalamus and produce prostaglandins. The body responds to the elevated set point by raising its temperature through shivering and vasoconstriction. In hyperthermia, the hypothalamic set point is normal, but the body has been warmed by external measures, such as a hot sun through a closed car window. When this situation occurs, the body tries to cool itself by vasodilation and sweating.


1. Mackowiak PA, Worden G: Carl Reinhold August Wunderlich and the evolution of clinical thermometry. Clin Infect Dis 1994;18:458

2. Herzog LW, Coyne LJ: What is fever? Normal temperature in infants less than 3 months old. Clin Pediatr (Phila) 1993;32(3):142

3. Mackowiak PA, Bartlett JG, Borden EC, et al: Concepts of fever: Recent advances and lingering dogma. Clinical Infectious Diseases 1997;25:119

4. Lorin MI: Fever: Pathogenesis and treatment, in Feigin RD, Cherry JD: Textbook of Pediatric Infectious Diseases, ed 4. Philadelphia, WB Saunders, 1998, pp 89-95

5. Blumenthal I: Fever—Concepts old and new. Journal of the Royal Society of Medicine 1997;90:391


What to do about fever

As long as your child is older than 3 months and there is an obvious reason why he (or she) feels warm—the presence of a cold, for example—it is usually unnecessary to take his temperature. You should take your child's temperature, however, if he is younger than 3 months or is not breathing, drinking, or acting as he normally does. If you are concerned about these activities, speak with your doctor, whether or not you detect a fever.

What type of thermometer to use

For a child younger than 3 months, use a digital rectal thermometer. It is safer than a glass thermometer and more accurate than other available thermometers.

If you choose to use a digital pacifier thermometer, be sure it stays in your infant's mouth for at least 31Ž2 minutes. You will also need to add 0.5° F to the reading to get a final measurement.

For a child between 3 months and 5 years, a digital rectal thermometer is the best choice. An armpit (called axillary) temperature, though not as accurate as a digital rectal reading, is also acceptable in this age group. If you use axillary measurements, add 1° F to the reading to get a rough estimate of rectal temperature.

An ear thermometer may be unreliable, especially in a child younger than 1 year of age. It may be used in children older than 1 year but is not as accurate as the rectal temperature.

For a child older than 5 years, use an oral digital thermometer if the child is willing to cooperate by holding it under the tongue for the required time.

When to give over-the-counter medicine for fever

If your child is uncomfortable and older than 3 months, you may start anti-fever medicine at any temperature elevation. If your child is younger than 3 months, call your pediatrician before starting any anti-fever medicine.

Acetaminophen is the only over-the-counter anti-fever medicine that should be used in a child younger than 6 months. Give it every four to six hours as needed. Ibuprofen may be given to children 6 months and older, every six to eight hours as needed. Both medicines should be given in a dose according to the instructions on the package or as directed by your health-care provider.

With any anti-fever medicine, check the label to see whether it is appropriate for a child, what medications it contains, and the frequency with which it should be given. Be aware that some cold medicines contain acetaminophen, so read the label carefully to avoid accidentally giving your child double the correct dose of acetaminophen. Measure doses of all medicines carefully to avoid dosing errors. Do not give aspirin, in any form, to an infant or child; it has been linked to Reye syndrome, a potentially fatal illness.

When to phone your health-care provider

Call the pediatrician if:

  • Your child is under 3 months and has a fever higher than 100.4° F (38° C).

  • Your child is lethargic or irritable or has a fever for longer than three days.

  • Your child complains of a sore throat or shows signs of ear pain.

  • Your child has additional symptoms, such as abdominal pain or pain upon urination.

  • Your child is not drinking fluids or has a decreased amount of urine.

  • You are worried about your child's breathing, level of activity, or intake or loss of fluids, whether or not your child has a fever.

The parent guide on fever can be photocopied and distributed to families in your practice without permission of the publisher.


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Jefferson Medical College, in accordance with accreditation requirements, asks the authors of CME articles to disclose any affiliations or financial interests they may have in any organization that may have an interest in any part of their article. The following information was received from the authors of "Fever: Measuring and managing a sizzling symptom."

Molly E. Rideout, MD, has nothing to disclose.

Lewis R. First, MD, has nothing to disclose.



Date of publication: May 2001
Title: Fever: Measuring and managing s sizzling sympton
Author: Molly E. Rideout, MD, and Lewis R. First, MD
MP Code: CP0501


Name: _______________________________________________   Degree: _______________

Street address: ____________________________   Institutional affiliation: ______________

City: _____________________   State: __________   ZIP: ___________   Telephone: __________

Specialty: [ ] Pediatrics   [ ] Other _________________ Years in practice: _________   Resident? ___

Time needed to complete this CME activity: [  ] <1 hr [  ] 1 hr [  ] 1.5 hr [  ] 2 hr

Certification: I attest to having completed this CME activity.

            Signature (required)   


1. Rate the overall effectiveness of this CME activity. 5 (very effective) 4  3  2  1 (not at all effective)

2. Circle "Yes" or "No"

A. The learning objectives were useful to me in determining whether performing this CME activity would be a worthwhile educational experience for me.
B. The objectives accurately described the content and potential learning value of this article.
C. This activity will influence how I practice medicine.
D. The activity was free from commercial bias.
E. I learned something new that was important from the article.

3. Which of the following best describes a change you might consider making in your practice as a result of something you learned from this activity? (Please circle only one response.)

A. Slightly modify what I currently do.
B. Make a major change in what I currently do.
C. Follow a procedure; use a technique/technology that is completely new to me.
D. Follow a procedure; use a technique/technology that I currently use but for a different purpose.
E. None of the above, but some change.
F. Not considering any changes.

4. Please describe any change(s) you plan to make in your practice as a result of this activity: ________



5. How committed are you to making these changes? 5 (very committed) 4   3   2   1  (not at all committed)

6. Other comments __________________________________________________________________


Circle A or B, and enclose payment if required.

A. I am a paid subscriber to Contemporary Pediatrics, so no payment is due.

The subscriber number above my name on the mailing label is: ___ ___ ___ ___ ___ ___ ___ ___

(Example: _1_ _2_ _3_ _4_ _5_ _6_ _7_ _8_ ).

If you do not know your subscriber number, please call 1-800-432-4570.

B. I am not yet a paid subscriber, so I am enclosing $20 to cover the cost of processing my CME application.

[ ] I am enclosing a check (payable to JMC/CME).

[ ] Please charge my Mastercard or Visa (circle type of card),

account number: ___ ___ ___ ___-___ ___ ___ ___-___ ___ ___ ___-___ ___ ___ ___ ,

expiration date: ___ ___ /___ ___

                                                              Signature (required)


Lewis First, Marianne Rideout. CME -- Fever: Measuring and managing a sizzling symptom. Contemporary Pediatrics 2001;5:42.

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