Fever itself is not an illness – it’s your body’s response to an infection as it creates immune cells to fight the infection3,4.

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What is Fever?

Humans have a normal core temperature of around 37° C when measured with a rectal thermometer1. Generally, the definition of a fever is a temperature that’s above 38° C when taken with a rectal thermometer2.

So fever itself is not dangerous and, in most cases, is actually good2,5.  However, not every rise in body temperature counts as a fever – body temperature varies throughout the day, according to your personal body rhythms, hormonal changes, how active you are and your metabolism6.

Mild fever

Is a temperature reading of 38° – 39° C4,7. A mild fever with no other symptoms is not a cause for concern and should not be treated2,4. The fever will usually clear up on its own after a few days2. However, with babies under 3 months, a fever of 38° C could indicate a serious illness and the baby should be taken to a healthcare provider as soon as possible4. The same applies for babies between the ages of 3 and 6 months whose temperature reaches 39° C or above and children of any age who have critical signs 4.

High fever

Is a temperature reading over 40° C and can be a sign that the child is at risk of having a more serious illness, such as meningitis7,8. If a  the child shows symptoms of an intermediate or high-risk fever, you should seek medical advice and use medication to relieve discomfort8.

Get medical help if a child shows any of these critical signs:

Immediate Risk
  • Looks pale8
  • Isn’t responding normally, for example struggling to make eye contact and not smiling8
  • Takes a long time to wake up8
  • Flaring nostrils8
  • Very rapid breathing8
  • Cracking in the chest8
  • Rapid heart rate8
  • Dry eyes, mouth and lips8
  • An infant doesn’t want to feed8
  • Less urine output8
  • Temperature is 39° C higher in babies age 3 – 6 months2, 8
  • Fever has lasted more than 5 days in older children2, 8
  • Stiffness8
  • Swelling in a joint or limb8
High Risk
  • Looks white or turning blue2,8
  • Unresponsive2,8
  • Won’t wake up or struggles to stay awake8
  • Weak, high pitched or continuous cry8
  • Grunting8
  • Difficulty breathing8
  • Skin is loose and sunken8
  • Rash that doesn’t fade when you press on it8
  • Top of the head (fontanelle) is bulging8
  • Stiff neck8
  • Seizures8
  • Temperature of 38°C or higher in a baby under three months2, 8

Febrile seizures

Some children between the ages of 6 months and 6 years old will have seizures that are triggered by fever9. This is the most common type of seizure in children9. While they may be concerning, these seizures usually only last a few minutes and are not serious9. Usually, no treatment is recommended for the actual seizure because it’s over so quickly10. Very rarely, a febrile seizure may go on for longer than 20 minutes, in which case anti-convulsive medication would be needed to stop it9.

Symptoms include:

  • Passing out
  • Difficulty breathing
  • Looking pale or turning blue
  • Foaming at the mouth
  • Eyes rolling back
  • Fixed gaze
  • Twitching or jerking
  • Afterwards the child is confused or irritable for about half an hour9.

If your child has a febrile seizure:

Follow the ABC protocol

  • Make sure their airway is clear, that they’re breathing and they have a pulse (circulation)11.
  • Take note of how long it lasts and all the symptoms that the child is displaying during the seizure, as your medical provider will need this information9.
  • If the seizure is still going after 10 minutes, it seems to be only one side of the body or it’s the second seizure within 24 hours, it could be a more serious type called a complex febrile seizure, and may require anticonvulsive medication to stop it9.

Know the Signs

In Adults12

  • Feeling warm
  • Shivering or chills
  • Body aches
  • Sleepy
  • Difficulty breathing
  • Thirsty
  • Weakness
  • Poor appetite

In Children2

  • Fatigue
  • Joint pain
  • Muscle aches
  • Loss of appetite
  • Confusion
  • Rapid pulse
  • Rapid breathing
  • Hot to the touch13
  • Constantly irritable or inconsolable13
  • Febrile seizures

It’s important to understand that, with children,  how the child looks – including the symptoms – is more important for establishing how serious the illness is than how the high their temperature is14.

Fever Triggers

Fevers are almost always caused by an infection – most often a harmless infection that will go away on its own4.

Other causes of fever may include:

Vaccination – People often report having a fever after receiving a vaccination.15.

Serious illnesses – Such as pneumonia, meningitis or septicemia4.

Get Diagnosed

A person may feel hot to the touch, as if they’re “burning up”, but that doesn’t necessarily indicate a fever13.

As a parent, putting your hand to your child’s forehead or neck can be a starting point, but you should then use a thermometer to get an accurate temperature13.

You can insert a thermometer rectally, orally, under the arm or get a special thermometer that goes in the ear and measures the temperature of the eardrum16. Dummies that have a built-in thermometer and forehead thermometers have been found to be inaccurate13,16.

Treating Fever

There’s no need to treat a mild fever since fever plays a role in fighting infection and the only reason for treating it is to relieve discomfort4. When the fever gets high enough to make the person feel uncomfortable, the fever can be treated to help them feel better – Treating the fever  will not get rid of the underlying cause of the fever8.

Treatment for fever includes:

Fluids

Avoid dehydration by drinking more as the temperature goes up16.

Plenty of rest

In a well-ventilated room16.

Light clothing

The person shouldn’t be underdressed or overwrapped8.

Medication

Is only necessary if the fever is above 40° C or causing discomfort; such as pain, confusion and weakness or tiredness14. You can use paracetamol or ibuprofen to lower the fever14,16. Dosage should be based on weight, rather than age17.

The don’ts when someone has a fever

Don’t sponge them with alcohol, it can be absorbed through the skin16.
Don’t put a fan on them, this can raise body temperature14.

A fever isn’t a medical condition on its own

Fever is a sign that your body is trying to fight off an infection5.

Washing your hands with soap has been shown to be effective for limiting your exposure to germs that cause infections18.

Medication dosage by weight

Recommended dosage for fever medication:

Ibuprofen: 5 – 10 mg/kg per dose8
Paracetamol: 10 – 15 mg/kg per dose8

A child weighing 10 kg should be given 50 – 100 mg of ibuprofen or 100 – 150 mg of paracetamol in a single dose.

Site Matters

Where you take a temperature reading makes a difference16. The following readings are considered a fever:

Rectal: Above 38° C
Oral: Above 37.5° C
Under the arm: Above 37° C
Ear: Above 37.9° C in children under 11 years; above 37.6° C in people 11 years and older16

References

  1. Osilla, E. V. et al. Physiology, Temperature Regulation. In StatPearls. StatPearls Publishing. (2020)
  2. Pearce, C. & Curtis, N. Fever in children. Aust Fam Physician. 34, 9.769-71. (2005)
  3. Bartfai, T. & Conti, B. Fever. Scientific World Journal. 16,10.490-503. (2010)
  4. De Ronne, N. La fiévre chez les enfants de moins de 3 ans [Management of fever in children younger then 3 years]. J Pharm Belg. Sep, 3.53-7. French. (2010)
  5. Chiappini, E.,et al. Guidelines for the symptomatic management of fever in children: systematic review of the literature and quality appraisal with AGREE II. BMJ Open. 7, 7. (2017)
  6. Balli, S. & Sharan, S. Physiology, Fever. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. (2020)
  7. Schmitt, B.D. Fever phobia: misconceptions of parents about fevers. Am J Dis Child. 134, 2.176-181. (1980)
  8. Kanabar, D. A practical approach to the treatment of low-risk childhood fever. Drugs in R&D14, 2. 45–55. (2014)
  9. Laino, D., et al. Management of Pediatric Febrile Seizures. Int J Environ Res Publ Health15, 10. 2232. (2018)
  10. Mewasingh, L. D. Febrile seizures. BMJ Clinical Evidence. 0324. (2014)
  11. Smith, D. K., et al. Febrile Seizures: Risks, Evaluation, and Prognosis. Am Fam Physician99, 7. 445–450. (2019)
  12. Ames, N. J. et al. A systematic approach for studying the signs and symptoms of fever in adult patients: the fever assessment tool (FAST). Health and quality of life outcomes15, 1. 84. (2017)
  13. Hague, R. Managing the child with a fever. The Practitioner259, 1784. 17–3. (2015)
  14. El-Radhi, A. S. Fever management: Evidence vs current practice. World J. Clin. Pediatr. 1, 4. 29–33. (2012).
  15. Katrin, S. et al. Fever after Immunization: Current Concepts and Improved Future Scientific Understanding. Clin. Infect. Dis. 39, 3. 389–394. (2004)
  16. Ng, D. K. et al. Childhood fever revisited. HKMJ = Xianggang yi xue za zhi8, 1. 39–43. (2002)
  17. Chiappini, E, et al. Management of fever in children: summary of the Italian Pediatric Society guidelines. Clin Ther. 31, 8.1826-43. (2009)
  18. Burton, M, et al. The effect of handwashing with water or soap on bacterial contamination of hands. J. Environ. Res. Public Health8, 1. 97–104. (2011).
  19. Cheshire, W. Thermoregulatory disorders and illness related to heat and cold stress. Auton Neurosci. 196. 91-104. (2016)

Learn more about other areas of pain.

Learn more about other areas of pain.