Understanding Fever – Fever is a medical condition characterized by an elevated body temperature above the normal range. A fever is generally considered to be a body temperature above 98.6°F (37°C) and is deemed significant when it goes above 100.4°F (38.0°C).
Cause of Fever
It is usually caused by an immune system response to a foreign invader, such as a virus, bacteria, fungi, drug, or toxin. In most cases, fever is beneficial and helps the body fight off infections. However, prolonged or high-grade fever can sometimes lead to complications.
Symptoms of fever may include sweating, chills, headache, muscle aches, and fatigue. In some cases, fever may also cause dehydration, especially in children.
Children under three months of age with a temperature of 100.4°F (38.0°C) or higher should be seen by a healthcare professional, as they may be quite ill and not display any other signs besides a fever. Infants younger than six weeks old should be brought to a doctor immediately.
Fever can be treated with over-the-counter drugs such as acetaminophen (Tylenol and others) or ibuprofen (Advil, Motrin). However, aspirin should not be given to children or teenagers to control fever, as it may cause a serious illness called Reye’s syndrome.
This picture shows a child with a fever and high temperature.
A fever, or pyrexia, is generally defined as a body temperature above 98.6 degrees Fahrenheit (37°C), but it’s considered significant only when it goes above 100.4°F (38.0°C).
Fever is usually beneficial and helps the body fight off infections. Its treatment is primarily to increase comfort. When a foreign invader such as viruses, bacteria, fungi, drugs, or other toxins enters the body, the immune system responds with a fever.
If a child under three months of age has a temperature of 100.4°F (38.0°C) or higher, they should be seen by a healthcare professional. Such infants may be seriously ill and not display any other symptoms besides a fever. Babies younger than six weeks old should be brought to a doctor immediately.
Fever can be treated with over-the-counter drugs such as acetaminophen (Tylenol and others) or ibuprofen (Advil, Motrin). However, aspirin should not be given to children or teenagers to control fever.
The prognosis of fever depends on the underlying cause.
Most fever cases are self-limited and can be resolved with symptom treatment. However, people with weakened immune systems due to immunosuppressant drugs or serious conditions like cancer, AIDS, heart disease, or diabetes should seek medical care if a fever develops.
Categorizing fevers can be challenging due to their numerous underlying causes.
Typically, fevers are classified based on their duration and peak temperature. Medical practitioners have identified five primary types of fever:
- Intermittent fever: This fever exhibits a fluctuating baseline, with temperatures alternating between normal and feverish levels throughout the day.
- Remittent fever: With this fever, temperature may come and go, and fluctuate, but it never returns entirely to normal once it falls.
- Hectic fever: If the temperature range swings widely throughout the day, with a difference of at least 1.4 degrees Celsius between the highest and lowest temperatures, either an intermittent or a remittent fever is considered hectic.
- Continuous fever: Also known as a “sustained” fever, this type of fever is prolonged and has minimal or no temperature variation throughout the day.
- Relapsing fever: This type of fever involves intermittent spikes of high temperature after periods of normal temperature lasting several days or weeks. It is often associated with diseases such as malaria or animal bites.
Lets Talk About What A fever is
A fever refers to an increase in body temperature or a high body temperature. Typically, any body temperature above the average oral measurement of 98.6 degrees Fahrenheit (37 Celsius) or rectal temperature of 99 F (37.2 C) is considered elevated, although an individual’s normal body temperature can vary up to 1 F (0.6 C) throughout the day.
Medical professionals consider a body temperature of 100.4 F (38 C) or higher to be a fever. Any temperature above normal but below 100.4 F (38 C) is considered a low-grade fever. Fever is a natural defense mechanism that helps fight off bacteria and viruses that cannot survive at higher temperatures. Low-grade fevers typically do not require treatment unless accompanied by concerning symptoms.
Fever is just one part of an illness, and other symptoms such as cough, sore throat, fatigue, joint pain or aches, chills, or nausea may also be present. Fevers of 104 F (40 C) or higher can be dangerous, particularly in infants, children, and the elderly, and require immediate medical attention as they can cause delirium and convulsions.
Fever should not be confused with hyperthermia, which is a defect in the body’s response to heat and can also raise body temperature. Heat exhaustion and heat stroke are examples of hyperthermia caused by external sources such as being in a hot environment. Certain medications or medical conditions can also cause hyperthermia.
Furthermore, fever should not be confused with hot flashes or night sweats caused by hormonal changes during perimenopause. Hot flashes and night sweats cause a sudden feeling of heat, flushing, and sweating, but they are not the same as a fever.
Discussion on Causes Of Fever
A fever occurs as a result of the immune system’s reaction to a foreign substance. These substances can be viruses, bacteria, fungi, drugs, or toxins, which are referred to as fever-producing agents or pyrogens. When the body detects pyrogens, it signals the hypothalamus in the brain to raise the body’s temperature in an effort to fight off the infection. Common infections that can cause a fever include colds, flu, and gastroenteritis, and exposure to infectious agents is a risk factor for developing a fever.
Various infections such as those affecting the ear, throat, lung, bladder, and kidney can also result in a fever. In some cases, immunizations, teething, or non-infectious causes like autoimmune disorders, medication side effects, seizures, blood clots, hormone disorders, cancers, or illicit drug use can lead to a fever. While fever itself is not contagious, if it is caused by a viral or bacterial infection, the infection can be contagious.
What are the signs and symptoms of fever?
Fever can cause discomfort and various symptoms, including:
- Temperature greater than 100.4 F (38 C) in adults and children
- Shivering, shaking, and chills
- Muscle and joint aches, headaches
- Sweating excessively or intermittently
- Rapid heart rate and/or palpitations
- Flushed or hot skin
- Feeling faint, dizzy, or lightheaded
- Eye pain or sore eyes
- Loss of appetite
- Fussiness in children and toddlers
It’s essential to note that children may also experience accompanying symptoms of infections, such as sore throat, cough, earache, vomiting, and diarrhea.
When should you be concerned about fever?
Here are some symptoms that indicate the need for medical attention:
- A fever over 104 F/40 C in children and adults is considered dangerous, and immediate medical attention is required.
- Children below three months of age with a temperature of 100.4 F (38 C) or higher should see a physician. Adults or children with a history of serious illnesses or taking immunosuppressant drugs should also seek medical care for fever.
- Children with fever and accompanying symptoms, such as rash, sore throat, ear pain, stiff neck, drowsiness, or headache, should see a doctor. If a fever lasts more than one day in children aged two years or younger, or more than three days in children over two years of age, medical care is necessary.
- Symptoms of a severe illness, such as meningitis (headache, stiff neck, confusion), urinary tract infection (chills, back pain, burning with urination), pneumonia (shortness of breath, cough), repeated vomiting, severe diarrhea, or skin rashes, should prompt a call to a healthcare professional.
- Pregnant women with a fever over 101 F (38 C) should contact their doctor immediately, especially if accompanied by rash and joint pain, which could be a sign of an infection that may harm the baby.
- Recurrent, persistent, or chronic fever in adults may indicate immune-deficient fever of unknown origin (FUO), neutropenic FUO, HIV-associated FUO, or other infectious conditions that require medical attention.
While some childhood vaccines may cause low-grade fever, it’s best to contact a doctor if the fever is severe or the injection site is painful. Febrile seizures associated with high fever can occur in some children and toddlers, but they are not associated with long-term complications. Recurrent fever in children may be a symptom of underlying conditions and require medical evaluation.
What is the process for diagnosing and measuring a fever?
To diagnose a fever, healthcare professionals typically check for generalized fever symptoms and confirm the diagnosis by taking a person’s temperature with a thermometer. In adults and children, a temperature greater than 100.4 F is considered a fever. If the cause of the fever needs to be treated, additional tests, such as blood and imaging tests, may be performed.
To measure a fever, digital thermometers are commonly used to measure rectal, oral, or axillary (under the armpit) temperatures. The American Academy of Pediatrics recommends against using mercury thermometers due to the risk of mercury exposure.
When measuring axillary temperature, the thermometer is placed in the armpit for about one minute or until a beep is heard. However, axillary temperatures are generally not as accurate as rectal or oral measurements and may read 1 degree lower than simultaneously obtained oral temperatures.
Tympanic (ear) thermometers may be used, but the accuracy can be affected by earwax. Additionally, eardrum temperature measurements should not be used in children under 3 years of age.
For oral temperature measurement, the thermometer is placed under the tongue with the mouth closed for about one minute or until a beep is heard. It is important to avoid hot or cold drinks within 15 minutes of taking an oral temperature to ensure accuracy.
Rectal temperature measurement is recommended for children and toddlers under 3 years of age since it gives the most accurate reading of core temperature. The thermometer is inserted approximately ½ to 1 inch into the rectum, held in place for about one minute until a beep is heard, and then removed for digital reading. Rectal temperature readings will typically be around 1 degree higher than simultaneously obtained oral temperatures.
What is the recommended treatment for a fever?
In most cases, if the fever is not causing discomfort, treatment is not necessary. Only a doctor’s instructions should prompt you to awaken an adult or child for fever treatment.
Over-the-counter fever-reducing medications can be used at home, such as:
- Acetaminophen (e.g. Tylenol) can be used to lower fever. The recommended dose varies based on age and health conditions. It is important to follow the instructions of a physician. If you have difficulty taking oral medications due to vomiting, acetaminophen suppositories are available without a prescription.
- Ibuprofen (e.g. Motrin, Advil) can also be used for fever reduction in patients over 6 months of age. The appropriate dose should be discussed with a doctor.
- Naproxen (e.g. Aleve) is another nonsteroidal anti-inflammatory drug (NSAID) that can temporarily reduce fever. The adult dose is two tablets every 12 hours.
It is important to note that aspirin should not be used for fever in children or adolescents as it can lead to a serious illness called Reye’s syndrome.
What are some home remedies for a fever?
Keeping the person comfortable and not overdressed is important as overdressing can cause the temperature to rise further. Tepid water (85 F [30 C]) baths or sponge baths can help bring down a fever. However, it is important not to immerse a person with a fever in ice water or sponge them with alcohol, as these methods can be harmful.
Staying hydrated by drinking plenty of fluids is crucial. Avoid alcohol or caffeinated beverages, which can contribute to dehydration. Popsicles can also be a soothing and cooling way to hydrate, especially if there is a sore throat.
Other home remedies include using a fan or opening a window for air circulation and applying a cool damp washcloth to the forehead. If caring for a child, make sure they do not feel too cold.
Can doctors from any specialty treat a fever?
While any doctor can technically treat a fever, it is most common for patients to seek care from their primary care physician, such as a family medicine specialist or internist. Children usually see a pediatrician for fever, and in emergency situations, patients may see an emergency medicine specialist. If a fever is caused by an underlying medical condition, a specialist in that area may be consulted, such as an oncologist for a cancer patient with a fever or an infectious disease specialist for a patient with HIV/AIDS and fever.
What are the potential complications of a fever?
While a fever itself typically does not cause severe complications, prolonged or high fevers can lead to seizures, hallucinations, and dehydration. It is important to seek treatment for the underlying cause of a fever, as many infections that cause fever can lead to serious complications if left untreated.
What is the prognosis for a fever?
The prognosis for a fever depends on its underlying cause. Most cases of fever resolve with symptomatic treatment within a few days, but fevers associated with severe infections or immune-compromised patients can be life-threatening. The use of appropriate medications, such as antibiotics, may be necessary depending on the cause of the fever.
Is it possible to prevent a fever?
Preventing a fever is possible only to the extent that the specific cause of the fever can be prevented. Most fevers are caused by infections, so practicing good hygiene, avoiding contact with sick people, and keeping up-to-date with vaccinations can help prevent the spread of infection and potentially prevent fevers from occurring.