Overview
Fever occurs when a person’s body temperature rises above the normal range. While the average body temperature is typically 37°C, it can vary from 35.9°C to 37.7°C depending on the method and location of measurement. For example, armpit readings may show a normal range between 35.9°C and 36.7°C, while ear measurements can go up to 37.5°C. Rectal measurements often register the highest, with normal temperatures reaching up to 37.7°C. A reading of 38°C or higher is generally considered a fever.
Doctors regard fever not as a disease but as a symptom indicating that the body’s immune system is fighting off an underlying condition or infection. Elevated body temperature helps eliminate viruses or bacteria that cannot survive in a warmer environment, making fever an essential defense mechanism.
Although fever itself is not a disease, it often comes with accompanying symptoms, such as chills, sweating, loss of appetite, dehydration, muscle or joint pain, headaches, fatigue, drowsiness, irritability, and difficulty concentrating. Most fevers are mild and resolve within 2 to 3 days with proper care, but they can persist for up to 14 days in some cases.
Managing fever typically involves taking over-the-counter medications such as paracetamol, acetaminophen, or ibuprofen to lower the temperature. For fevers caused by infections, doctors may prescribe antivirals or antibiotics depending on the underlying cause. Additionally, staying hydrated, resting, and applying a cool compress to the body can help reduce fever and promote recovery.
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Possible Causes of Fever
Fever often signals that the body is fighting an underlying condition, most commonly an infection. However, various other factors can also cause a rise in body temperature. Below are the common causes of fever:
- Infections. Infections caused by viruses or bacteria are the most common causes of fever. Viral infections like the common cold and tonsillitis, or bacterial infections such as urinary tract infections (UTIs) and respiratory illnesses, often result in elevated body temperature.
- Exposure to extreme heat. Prolonged exposure to high temperatures, such as during heatwaves or direct sunlight, can lead to heatstroke. Fever is one of its symptoms, and body temperature can spike as high as 40.5°C, potentially causing fainting.
- Inflammatory conditions. Autoimmune disorders, such as rheumatoid arthritis, can cause joint pain and inflammation, often accompanied by mild fever as the immune system responds to the affected areas.
- Cancer. Fever may occur in patients with advanced cancer, particularly blood cancers such as leukemia and lymphoma. While fever is rare in early-stage cancers, it becomes more common as the disease progresses.
- Medication side effects. Certain medications, such as antibiotics, seizure medications, and drugs for high blood pressure, can temporarily elevate body temperature as a side effect.
- Vaccination reactions. Mild fever is a common response to vaccinations, especially in children and infants, as the body builds immunity to the pathogens introduced by the vaccine.
- Gallbladder diseases. Conditions like gallstones, choledocholithiasis (stones in the bile duct), and cholecystitis (inflammation of the gallbladder) can cause fever as part of the body’s response to infection or inflammation.
- Liver diseases. Conditions such as hepatitis, jaundice, infant jaundice, and Reye’s Syndrome may result in fever due to liver dysfunction and inflammation.
- Skin conditions. Fever can accompany infections like chickenpox, leptospirosis, and boils, as these involve the body’s immune response to skin-related infections.
- Respiratory illnesses. Diseases such as tonsillitis, pneumonia, sarcoidosis, the common cold, and tuberculosis often trigger fever as a symptom of infection or inflammation in the respiratory system.
- Kidney diseases. Conditions like kidney infections, lupus, proteinuria, kidney stones, and UTIs can cause fever due to inflammation or infection in the urinary system.
- Neurological conditions. Meningitis, an infection or inflammation of the brain and spinal cord membranes, is often accompanied by fever as the body fights the infection.
- Sexually transmitted diseases (STDs). Infections such as HIV/AIDS, chlamydia, and syphilis may lead to fever as part of the body’s systemic immune response.
- Ear infections. Infections like otitis media and other ear-related conditions can cause fever as the immune system combats the infection.
- Tropical diseases. Conditions such as COVID-19, African swine fever, dengue, malaria, typhoid fever, rabies, SARS, and Middle East Respiratory Syndrome (MERS) are common in tropical areas and often present with fever as a primary symptom.
Identifying the underlying cause of fever is crucial for effective treatment. If fever persists, worsens, or is accompanied by severe symptoms, seeking medical advice is essential to ensure appropriate care.
When to See a Doctor
Fever is often a temporary symptom that resolves on its own, but there are situations when medical attention is necessary. Consult a doctor if:
- The fever persists for more than three days. A prolonged fever could indicate a serious underlying condition that requires diagnosis and treatment.
- The body temperature reaches 39.4°C (103°F) or higher. Extremely high fevers may cause complications or signal severe infections.
- Other severe symptoms accompany the fever. Symptoms such as difficulty breathing, severe headaches, confusion, chest pain, seizures, persistent vomiting, or a stiff neck warrant immediate medical attention.
- The fever occurs in a very young child or an elderly person. Infants under three months with a fever above 38°C (100.4°F) and seniors with weakened immune systems should be evaluated promptly.
- You experience recurring fevers. Fevers that come and go over time could indicate a chronic condition or ongoing infection that requires investigation.
- A skin rash develops alongside the fever. Certain infections like measles, chickenpox, or meningitis present with both fever and rash, necessitating medical intervention.
What Type of Doctor to Seek
A general practitioner or family physician can evaluate the fever and perform necessary tests to determine its cause. Depending on the findings, they may refer you to:
- An infectious disease specialist for severe infections.
- A pediatrician for children experiencing fever.
- A neurologist for fever with neurological symptoms like seizures or confusion.
- An oncologist if cancer-related fever is suspected.
What to Expect From Your First Doctor Visit
During your visit, the doctor will:
- Review your medical history and symptoms.
- Conduct a physical examination, checking for signs like rashes, inflammation, or neurological issues.
- Order diagnostic tests such as blood tests, urinalysis, imaging, or cultures to identify infections or underlying conditions.
The doctor will provide recommendations based on the findings, which may include medication, hydration, or further specialist consultations. Seeking timely medical attention ensures proper diagnosis and treatment, reducing the risk of complications.
Fever FAQs
Fever is a common condition that raises many questions. Here are the most frequently asked questions about fever and their answers:
1. What is a fever?
Fever is a temporary increase in body temperature, often due to an infection or illness. It’s a sign that your body is fighting off harmful microorganisms or inflammation.
2. What temperature is considered a fever?
A body temperature of 38°C (100.4°F) or higher is generally considered a fever. However, the exact threshold may vary depending on the method of measurement.
3. What causes a fever?
Fever can be caused by infections (bacterial or viral), inflammatory conditions, heat exhaustion, certain medications, vaccinations, or underlying diseases like cancer or autoimmune disorders.
4. Is fever dangerous?
Mild to moderate fevers are usually not dangerous and can help the body fight infections. However, high fevers above 39.4°C (103°F) or prolonged fevers may lead to complications and should be evaluated by a doctor.
5. How can I treat a fever at home?
To manage fever at home, stay hydrated, rest, and take over-the-counter medications like paracetamol or ibuprofen. Cool compresses and lightweight clothing can also help reduce body temperature.
6. When should I seek medical help for a fever?
You should consult a doctor if the fever persists for more than three days, is very high (above 39.4°C or 103°F), or is accompanied by severe symptoms like difficulty breathing, seizures, or persistent vomiting.
7. Can stress cause a fever?
Stress is not a direct cause of fever, but it can weaken the immune system, making the body more susceptible to infections that may cause fever.
8. Why do some people get chills with a fever?
Chills occur when the body tries to raise its temperature by contracting muscles, signaling that the body is working to fight off an infection.
9. Can fever be a symptom of COVID-19?
Yes, fever is a common symptom of COVID-19, along with cough, fatigue, and loss of taste or smell. It’s important to get tested if you suspect you may have COVID-19.
10. Can a fever come back after it goes away?
Yes, recurring fevers may indicate an ongoing infection, autoimmune disease, or other chronic conditions that require medical attention.
If you have persistent or unexplained fever, consult a healthcare professional to determine the underlying cause and receive appropriate treatment.
