Causes of Prolonged Fever Explained
Understand the common and serious causes of prolonged fever, from infections and autoimmune conditions to chronic illnesses. Learn how it’s diagnosed, tips to manage symptoms at home, and when to seek medical attention for proper evaluation and treatment.
Written by Dr. Siri Nallapu
Reviewed by Dr. Dhankecha Mayank Dineshbhai MBBS
Last updated on 22nd Aug, 2025
Introduction
Fever is a common symptom that most of us experience at some point in our lives. It’s usually a sign that your body is fighting an infection or illness. However, when a fever lasts for more than a few days, typically beyond 7 to 10 days, it’s considered a prolonged fever. This can be concerning, and understanding the possible causes can help you take the right steps toward recovery.
In this article, we’ll explore the common reasons behind prolonged fever, when to seek medical help, and what you can do to manage it.
What is a Prolonged Fever?
A prolonged fever is when an elevated body temperature (usually above 100.4°F or 38°C) persists for an extended period, often more than a week. Unlike a short-lived fever caused by common infections like the flu or a cold, a prolonged fever may indicate a more serious underlying condition that requires medical attention.
Consult a Top General Physician for the best advice
Common Causes of Prolonged Fever
Prolonged fever can be caused by various factors, including infections, inflammatory conditions, and even certain medications. Here are some of the most common causes:
1. Infections
Infections are the most frequent cause of prolonged fever. These can include:
Bacterial Infections:
- Tuberculosis (TB)
- Urinary tract infections (UTIs)
- Pneumonia
- Typhoid fever
- Sinus infections
Viral Infections:
- Epstein-Barr virus (mononucleosis)
- Cytomegalovirus (CMV)
- Dengue fever
- HIV
Parasitic or Fungal Infections:
- Malaria
- Toxoplasmosis
- Fungal infections (e.g., histoplasmosis)
2. Autoimmune & Inflammatory Diseases
Sometimes, the immune system mistakenly attacks healthy tissues, leading to prolonged fever. Conditions include:
- Rheumatoid arthritis
- Lupus (SLE)
- Inflammatory bowel disease (IBD)
- Vasculitis (inflammation of blood vessels)
3. Cancers
Certain cancers can cause persistent fever, including:
- Leukemia
- Lymphoma
- Kidney or liver cancer
4. Medication-Induced Fever
Some drugs can cause fever as a side effect, including:
- Antibiotics (e.g., penicillin)
- Antiseizure medications
- Blood pressure medications
5. Other Causes
Other causes of prolonged fever include:
- Chronic infections (e.g., abscesses)
- Endocrine disorders (e.g., hyperthyroidism)
- Heat-related illnesses (e.g., heatstroke)
When Should You See a Doctor?
While mild fevers often resolve on their own, you should seek medical attention if:
- The fever lasts more than 3-4 days in adults or more than 24-48 hours in children.
- The fever is very high (above 103°F or 39.4°C).
- You experience severe headache, rash, difficulty breathing, or confusion.
- You have weight loss, night sweats, or fatigue along with fever.
If you’re unsure, it’s always best to consult a doctor for proper evaluation.
How is Prolonged Fever Diagnosed?
Since prolonged fever can have many causes, doctors use different tests to find the root issue, such as:
- Blood tests (to check for infections, inflammation, or autoimmune conditions)
- Urine tests (to detect UTIs or kidney problems)
- Imaging tests (X-rays, CT scans, or ultrasounds to check for infections or tumors)
- Biopsies (if cancer or certain infections are suspected)
How Can You Manage Prolonged Fever?
While treating the underlying cause is essential, here are some general tips to manage fever at home:
- Stay Hydrated – Drink plenty of water, herbal teas, or ORS to prevent dehydration.
- Rest – Your body needs energy to fight infections, so avoid overexertion.
- Use Fever-Reducers – Medications like paracetamol (acetaminophen) can help, but avoid self-medicating for long periods.
- Cool Compresses – Apply a damp cloth to your forehead or take a lukewarm bath to bring down the temperature.
- Monitor Symptoms – Keep track of your fever pattern and any new symptoms to share with your doctor.
When to Avoid Home Remedies
If your fever is very high, persistent, or accompanied by severe symptoms, do not rely solely on home care; seek medical help immediately.
Final Thoughts
A prolonged fever can be a sign of various health conditions, from infections to chronic illnesses. While some cases resolve with simple care, others need medical intervention. If you or a loved one has been experiencing a persistent fever, don’t ignore it; consult a doctor to get the right diagnosis and treatment.
Consult a Top General Physician for the best advice
Consult a Top General Physician for the best advice
Dr. Abhishek Gowda
General Physician/ Internal Medicine Specialist
2 Years • MBBS
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Dr. Sangeeta Banik
General Physician/ Internal Medicine Specialist
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Dr. Tanzeem Shajahan
General Physician/ Internal Medicine Specialist
7 Years • MBBS, MD (General Medicine)
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Dr. Imtiyaz Khan
General Physician/ Internal Medicine Specialist
6 Years • MBBS,MD
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Bhargavi Hari B
General Physician/ Internal Medicine Specialist
7 Years • MBBS, MD
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
Consult a Top General Physician for the best advice
Dr. Abhishek Gowda
General Physician/ Internal Medicine Specialist
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Sangeeta Banik
General Physician/ Internal Medicine Specialist
9 Years • MBBS
Kolkata
CG INCURE, Kolkata
Dr. Tanzeem Shajahan
General Physician/ Internal Medicine Specialist
7 Years • MBBS, MD (General Medicine)
Bengaluru
Medwin multispeciality clinic, Bengaluru
Dr. Imtiyaz Khan
General Physician/ Internal Medicine Specialist
6 Years • MBBS,MD
Bengaluru
Apollo Clinic, Sarjapur Road, Bengaluru
Bhargavi Hari B
General Physician/ Internal Medicine Specialist
7 Years • MBBS, MD
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
