Understanding Pyrexia and Its Causes
Understand pyrexia (fever), its common causes, symptoms, and when it signals a serious condition. Learn how to manage and treat fever effectively in both adults and children.
Written by Dr. Vasanthasree Nair
Reviewed by Dr. Mohammed Kamran MBBS, FIDM
Last updated on 28th Jul, 2025
Understanding Pyrexia and Its Causes
Pyrexia, commonly known as fever, is a condition where your body temperature rises above the normal range (typically 98.6°F or 37°C). While fever is often a sign that your body is fighting an infection, it can also result from other underlying health issues. Understanding pyrexia, its causes, and how to manage it can help you take better care of yourself and your loved ones.
What Is Pyrexia?
Pyrexia is not an illness itself but a symptom of an underlying condition. It occurs when your body’s internal thermostat (the hypothalamus) raises your temperature to help fight infections or respond to other triggers. A mild fever is usually harmless and can even be beneficial, but a very high fever may require medical attention.
Common Symptoms of Pyrexia
- Elevated body temperature (above 100.4°F or 38°C)
- Chills or shivering
- Sweating
- Headache
- Muscle aches
- Fatigue or weakness
- Loss of appetite
- Dehydration
In children, fever may also cause irritability, lethargy, or seizures (febrile seizures) in rare cases.
What Causes Pyrexia?
Fever can be triggered by various factors, including:
1. Infections (Most Common Cause)
- Viral infections (flu, common cold, COVID-19, dengue)
- Bacterial infections (urinary tract infections, pneumonia, strep throat)
- Parasitic or fungal infections
2. Inflammatory Conditions
- Autoimmune diseases (rheumatoid arthritis, lupus)
- Inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
Consult Top Specialists
3. Heat-Related Illnesses
- Heat exhaustion or heatstroke (due to prolonged exposure to high temperatures)
4. Medications
Some antibiotics, antihistamines, or vaccines can cause a mild fever as a side effect.
5. Other Causes
- Blood clots
- Certain cancers
- Hormonal disorders
When Should You See a Doctor?
Most fevers resolve on their own with rest and hydration. However, seek medical attention if:
Adults:
- - Fever exceeds 103°F (39.4°C)
- - Fever lasts more than 3 days
- - Severe headache, stiff neck, confusion, or difficulty breathing
Children & Infants:
- - Infants under 3 months with a fever (100.4°F or higher)
- - Children with a fever above 104°F (40°C)
- - Fever with rash, seizures, or persistent vomiting
How to Manage Pyrexia at Home?
\Here’s how to manage pyrexia at home:
1. Stay Hydrated
- Drink plenty of water, herbal teas, or oral rehydration solutions.
- Avoid caffeine and alcohol, as they can worsen dehydration.
2. Rest
- Your body needs energy to fight infections, so take adequate rest.
3. Use Fever-Reducing Medications
- Over-the-counter medicines like paracetamol (acetaminophen) or ibuprofen can help lower fever.
- Always follow dosage instructions and avoid aspirin for children.
4. Cool Compresses
- Apply a damp cloth to your forehead or take a lukewarm bath to bring down body temperature.
5. Wear Light Clothing
- Avoid heavy blankets; opt for breathable fabrics to prevent overheating.
Preventing Fever
While not all fevers can be prevented, you can reduce the risk by:
- Practising good hygiene (washing hands frequently)
- Staying up-to-date with vaccinations (flu shot, COVID-19 vaccine)
- Avoiding close contact with sick individuals
- Managing chronic conditions (like diabetes or autoimmune disorders)
When to Consult a Doctor?
If your fever persists, worsens, or is accompanied by concerning symptoms, it’s best to consult a healthcare professional. Apollo24|7 offers convenient online consultations and lab tests to help diagnose the cause of persistent fever.
Conclusion
Pyrexia is usually a sign that your body is fighting an infection, and most fevers resolve with simple care. However, persistent or high-grade fever should not be ignored. By staying informed and taking the right steps, you can manage fever effectively and ensure a speedy recovery.
Consult Top Specialists
Consult Top Specialists
Dr. Suraja Nutulapati
General Physician/ Internal Medicine Specialist
10 Years • MBBS, MD (Internal Medicine)
Hyderabad
Apollo 24|7 Clinic, Hyderabad
(850+ Patients)
Dr. Mohammed Huzef Ul Arifeen
General Practitioner
3 Years • MBBS
Hyderabad
Apollo 24|7 Clinic - Telangana, Hyderabad
Dr Summaiya Banu
General Practitioner
8 Years • MBBS
Hyderabad
Apollo 24|7 Clinic, Hyderabad
(150+ Patients)
Dr. Siri Nallapu
General Practitioner
5 Years • MBBS
Hyderabad
Apollo 24|7 Clinic, Hyderabad
Dr. Lakshmi Sanjitha Kakani
General Physician/ Internal Medicine Specialist
6 Years • MBBS, MD (General Medicine)
Visakhapatnam
Apollo 24|7 Clinic - Andhra Pradesh, Visakhapatnam
