1.Introduction about fever:
Fever is defined as a condition that occurs when the body temperature rises above the normal temperature range. Fever is usually the body’s response to a disease-causing agent.
The average body temperature is 98.6 Fahrenheit (37 Celsius).
Typical body temperature can range between 97 F (36.1 C) and 99 F (37.2 C)
The age, the time of the day and the activity you are doing contribute to your body changes in normal range. Babies and children have higher temperatures than adults and older people have lower body temperatures than younger people.
You should considered a fever by age and temperature as below:
| Babies age 0-2 years | 100.4 F (annus, forehead, or ear temperature)99 F (armpit) |
| Children ages 2-5 years | 100.4 F (annus, forehead, or ear temperature)99 F (armpit) |
| Children ages 5 and older | 100.4 F (ear temperature)100 F (oral temperature)99 F (armpit) |
| Adults | 100.4 F (oral temperature) |
Fahrenheit-Celsius conversion table
| Fahrenheit | Celsius |
| 105 | 40.6 |
| 104 | 40.0 |
| 103 | 39.4 |
| 102 | 38.9 |
| 101 | 38.3 |
| 100 | 37.8 |
| 99 | 37.2 |
| 98 | 36.7 |
| 97 | 36.1 |
| 96 | 35.6 |
2. Fever as the body’s natural defense
Fever is considered the body’s natural defense to eliminate pathogens, most commonly bacteria and viruses.
The first and simplest mechanism is that when our body temperature is higher than the maximum tolerance threshold of pathogens such as bacteria and viruses, they cannot replicate and continue to live. Then the number of pathogens will be less, our immune system will work less hard, and therefore, the duration of infection will be shorter.
Fever increases the body’s immune response, including the innate immune response and the human immune response. Fever stimulates the process of white blood cell aggregation to the infected tissue to destroy pathogens. White blood cells increase their ability to migrate under the influence of cytokines produced by immune-protective mechanisms during infection.
One important mechanism in the immune response is phagocytosis, in which immune cells such as neutrophils and macrophages engulf pathogens such as bacteria and viruses, neutralize them, and remove them from the body. A study shows that fever helps phagocytosis work more vigorously. [1]
Fever increases the growth of T cells, which are the most powerful adaptive immune cells in the human body and are essential for survival. As vigilant killers, T cells are able to effectively distinguish harmful foreign invaders from healthy human cells. T cells have many surface receptors and can only bind to substances capable of inducing an immune response found on normal cells in the body and on viruses, bacteria, and tumors. When a T cell receptor matches a viral antigen on an infected cell, the cytotoxic T cell secretes a cytotoxin to kill the cell.
Some bacteria are surrounded by a capsule, when it breaks, the substances inside enter the body and release toxins. Fever also reduces the toxicity of bacteria and viruses in the body, contributing to many of the body’s natural defense mechanisms.
3. How to measure fever accurately
There are 5 common positions on the body that can measure temperature including: anus, oral, armpit, forehead and ear. Depending on the position, we choose the appropriate type of thermometer such as contact thermometer (thermometer touches directly to the skin or mucous membrane) and non-contact type (thermometer does not touch the skin and mucous membrane)
Anus: This is the most accurate temperature measurement position. This position is suitable for children under 5 years old. It is necessary to measure 15 minutes after eating to avoid food increasing the anal temperature, the result will be inaccurate.
- Turn on the digital thermometer and apply kerosene or other lubricant to the tip of the thermometer.
- Place the child on his stomach or side, knees bent.
- Carefully insert the thermometer tip 1/2 to 1 inch (1.3 to 2.5 cm) into the rectum.
- Hold the thermometer in your hand and keep the child still until the thermometer beeps, meaning it is done. To avoid injury, do not release the thermometer while it is still in the child. Usually less than 1 minute.
- Remove the thermometer and read the number.
Oral: Suitable for children over 5 years old and adults, using a contact thermometer. The results are quite accurate. Note that do not drink anything within 10 minutes before measuring. For people who have the habit of breathing through the mouth, this method may not be accurate, choose another measuring position.
- Turn on the digital thermometer. Place the thermometer tip under the tongue.
- Close the mouth around the thermometer for as long as instructed or until you hear the thermometer beep, which means it’s done.
- Remove the thermometer and read the number.
Armpit: This position can be used to measure body temperature with a contact thermometer when we cannot measure in the annus or oral. However, you should note that armpit temperatures are typically 0.5 to 1 degree Fahrenheit lower than oral temperatures.
- Turn on the digital thermometer. Place the thermometer under the armpit, making sure it touches skin, not clothing.
- Hold the thermometer tightly in place until you hear the thermometer beep, which means it’s done.
- Remove the thermometer and read the number.
Ear and forehead: These two positions are used to measure body temperature with a non-contact thermometer. Non-contact thermometers use an infrared scanner to measure the temperature of the temporal artery in the forehead (temporal artery) or the ear (tympanic). This thermometer is often used in schools, companies, hospitals or public places when it is necessary to screen the temperature of students or visitors. It gives quick results and is suitable for any age. However, the accuracy is not as high as a contact thermometer, its price is expensive and the results can be distorted due to many factors such as sunlight, wet skin on the forehead or cold weather.
- Forehead: Turn on the digital thermometer. Gently sweep it across the forehead and read the number.
- Ear: Turn on the digital thermometer. Gently place it in the ear canal only as far as the instructions. Hold the thermometer tightly in place until you hear the thermometer beep, which means it’s done. Remove the thermometer and read the number.
You need to label the thermometer for separate use in the armpit, mouth and rectum. Wash the thermometer after each use. Mercury contact thermometers are no longer used because of their fragility and the toxicity of mercury. If you have a mercury thermometer, do not throw it in the trash but send it to a health center for safe disposal.
3. Fever thresholds that require medical attention
Fever in children in some cases is related to dangerous diseases that can cause death within 24 hours, such as meningococcal meningitis, sepsis, shock – cardiovascular collapse, etc. Therefore, when children have a fever, parents need to monitor their body temperature, reduce the fever properly and record the accompanying symptoms when the child has a fever. If the child has the following signs, parents need to take the child to the hospital for support from doctors as soon as possible:
- Fever in children under 2 months old
- Fever in children any age with temprature over 100.4 F
- High fever lasting more than 72 hours;
- Fever in children with one of signs: dehydration, convulsions, stiff neck, severe headache, skin rash, vomiting a lot, loss of consciousness, drowsiness, difficult to wake up, lethargic sleep, crying a lot, difficulty breathing, unable to breastfeed, swallow food or drink water.
Fever in adults usually goes away on its own after 1 to 3 days. A fever that lasts longer than usual can be serious, even if it is mild. You should seek medical advice if you have:
- A high fever 103°F (39.4°C) or higher
- Fever that lasts more than 3 days
- Symptoms that get worse, or new symptoms appear as: severe headache, dizziness, confusion,seizures, painful urination, insufficient urination, dark urine, stiff neck, difficulty breathing.
4. Common causes of fever in children and in adults
Causes of fever in children include:
- Infection: When infected, it can stimulate natural defense mechanisms by increasing body temperature, fever.
- Wearing clothes that are too tight or too thick: This condition is common in infants because they cannot yet regulate their body temperature as well as older children. Therefore, parents need to pay attention to dressing their infant in cool, sweat-absorbent clothes, avoiding dressing them too tightly, causing a feeling of stuffiness. When detecting that a newborn has a fever, parents need to take the child to the hospital for examination.
- Vaccination: Some children may have a mild fever after vaccination. However, if the child has a high fever above 38.5 degrees Celsius and shows no signs of cooling down after taking fever-reducing medicine, the child should be taken to the nearest medical facility.
- Teething: Usually, children will have a mild fever when teething. At this time, the child’s body temperature fluctuates between 38 – 38.5 degrees Celsius.
- Infectious diseases caused by viruses: colds, flu, …
- Side effects of some drugs.
- Children have just received a blood transfusion …
Cause fever in adult: Common causes of fever in adults include:
- Viral infections (such as the flu or a cold)
- Bacterial infections
- Fungal infections
- Food poisoning
- Heat exhaustion (heatstroke, sunstroke)
- Severe sunburn
- Inflammation (from conditions such as rheumatoid arthritis)
- Tumors
- Blood clots.
Some adults with chronic conditions are at high risk for severe fever and should tell their doctor if they develop a fever:
- Asthma
- Rheumatoid arthritis
- Diabetes
- Crohn’s disease
- Heart disease
- Sickle cell disease
- Liver disease
- Kidney disease
- Chronic lung disease
- Cystic fibrosis
- Cerebral palsy
- Stroke
- Multiple sclerosis
- Muscular dystrophy
- HIV or AIDS.
Certain medications and treatments can also cause fever in adults, including:
- Antibiotics
- Blood pressure medications
- Seizure medications
- DTaP vaccine
- Pneumococcal vaccine
- Steroids
- Chemotherapy
- Radiation treatment
- Methotrexate
- Azathioprine
- Cyclophosphamide
- Anti-rejection medications after organ transplants.
5. Treatment and home remedies
Non-drug treatment for fever: for fevers below 38 degrees, you can reduce the fever at home by using non-drug methods, including:
- Rest in a well-ventilated room.
- Wear comfortable, absorbent clothes. Note that wearing clothes that are too warm, too tight, or too thick will make it difficult for heat dissipation and perspiration to occur.
- Supplement enough water and electrolytes.
- Use a soft towel soaked in warm water to wipe the body for 5-15 minutes/time, focusing on the forehead, armpits and groin to help the pores expand, making it easier for heat to be pushed out. Note, only use warm water to wipe the body, do not use cold water or ice because the sudden difference in temperature will cause frostbite and respiratory failure.
- Monitor the temperature, re-measure the body temperature every 1-2 hours.
- Supplement enough nutrients, vitamins and minerals for children in each meal.
Medications treatment for fever:
There are two groups of over-the-counter medications that are used to reduce fever when a person is uncomfortable. They are acetaminophen (Tylenol, others) or NSAIDs (ibuprofen (Advil, Motrin ..). These medications are used for children over 6 months and adults. Only one of the two should be used. Read the instructions on the label carefully. If you or your child has a chronic medical condition, consult your medical doctor before using any medication.
6.Final thought
Fever is not a disease but a natural defense mechanism of the body, usually against infection. It is important to understand how to care for children and adults with fever and recognize the danger signs that require hospitalization.
References:
- Evans SS, Repasky EA, Fisher DT. Fever and the thermal regulation of immunity: the immune system feels the heat. Nat Rev Immunol. 2015 Jun;15(6):335-49. doi: 10.1038/nri3843. Epub 2015 May 15. PMID: 25976513; PMCID: PMC4786079.