Home General Medicine Pyrexia: Causes, Symptoms & Treatment

Pyrexia: Causes, Symptoms & Treatment

Verified By Apollo Doctors October 24, 2021 35628 0

Pyrexia, often known as fever, is a condition in which a person’s body temperature rises above the normal range. Even though an increase in body temperature can be a cause of concern, Pyrexia is a normal defense mechanism used by the human body to combat diseases.

Pyrexia, at times, is accompanied by additional symptoms such as fatigue, headaches, cough, and a cold. 

What is pyrexia?

Pyrexia is the body’s natural immunological response to disease-causing germs and serious illnesses. The human body’s normal temperature is 98.6°F and is normally taken from the oral or axillary region as well as the rectum. 

What are the different types of pyrexia?

Since there are many different causes of pyrexia, it can be difficult to categorize them, and the classifications aren’t always helpful. 

Doctors have identified five distinct forms of fever:

  1. Intermittent fever- This fever has a fluctuating baseline between normal temperatures and fever levels throughout the day.
  2. Remittent fever- This sort of fever may come and go, and the temperature may vary, but it never completely returns to normal.
  3. Hectic fever- Hectic fever is diagnosed when the body temperature fluctuates widely throughout the day, with a difference of at least 1.4 degrees Celsius between the highest and lowest temperatures, 
  4. Continuous fever- A protracted fever with little or no variation in temperature over a day is termed as a “continuous” or “sustained” fever.
  5. Relapsing- This is a type of intermittent fever that recurs after a period of normal temperature (days or weeks). Mosquito bites and infections like malaria are major causes of this sort of fever.

What are the common symptoms of pyrexia?

You get a fever when your temperature rises above the normal range. Additional fever signs and symptoms, depending on what’s causing your temperature, may include:

Frequent febrile seizures can occur in children aged 6 months to 5 years. Around a third of children who have experienced one episode of febrile seizure will have another one within the next 12 months.

When should you seek medical attention? 

Pyrexia isn’t always a cause for concern – or a reason to see a doctor. However, there are times when you should seek medical help for your newborn, kid, or yourself.


  • In infants and toddlers, an unexplained fever is more concerning than in adults. If your child is younger than 3 months old and has a rectal temperature of 100.4 F (38 C) or above, you should consult the doctor.
  • For babies and toddlers between the ages of 3 and 6 months, who have a rectal temperature of up to 38.9°C (102°F) and appear irritable, sluggish, or uncomfortable, or a temperature of more than 102 degrees Fahrenheit (38.9°C), medical attention is needed.
  • For toddlers, between the ages of 6 to 24 months, who have a rectal temperature of more than 102°F (38.9°C) for more than one day but exhibit no other symptoms, medical attention is needed.


If your infant has a temperature but is alert, making eye contact with you and responding to your facial expressions and voice, as well as drinking fluids and playing, there’s generally nothing to worry about.

If your child is experiencing any of the following symptoms, call 1860-500-1066 to book an appointment at Apollo Hospitals

  • Is irritable or listless, vomits frequently 
  • Has a strong headache or stomachache, or has any other symptoms that cause significant pain
  • Have had a fever for more than three days
  • Has a drowsy demeanor and has difficulty maintaining eye contact


If your temperature rises to 103°F (39.4°C), you should see your Apollo doctor immediately. If any of the following symptoms accompany a fever, seek medical help right away:

  • Severe headache
  • Unusual skin rash
  • Sensitivity to intense light
  • Neck stiffness and soreness when bending forward
  • Confusion or disorientation
  • Constant vomiting
  • Breathing problems or chest pain
  • Pain in the abdomen or during urinating
  • Seizures or convulsions

What causes pyrexia? 

Pyrexia can be caused by infectious or non-infectious causes. The following are some of the most common causes of pyrexia:

Infectious Causes:

  • Bronchitis and other diseases of the lower respiratory tract (inflammation of the air tubules that carry blood in and out of the lungs)
  • Tuberculosis (TB) is a bacterial lung infection that can cause pyrexia
  • Infections of the urinary tract
  • Osteomyelitis is a form of bone infection that can cause a fever
  • Endocarditis is a bacterial infection of the heart tissue which usually leads to pyrexia
  • Infections caused by viruses such as HIV (Human Immunodeficiency Syndrome) and Cytomegalovirus
  • Other bacterial and viral infections 

Non-Infectious Causes:

  • Brain fever and hemorrhages are examples of neurological diseases which can lead to pyrexia
  • Leukemia and renal cell carcinoma are examples of cancerous illnesses which can cause this condition
  • Side-effects from drugs
  • Problems with the bowels of the bladder
  • Blood transfusion reactions

What are the complications associated with leaving pyrexia untreated?

Fever-induced convulsions (febrile seizures) are common in children aged 6 months to 5 years old, and they frequently entail the loss of consciousness and uncontrolled shaking of both sides of the body. The majority of febrile seizures have no long-term consequences.

If your infant experiences a seizure, you can do the following:

  • Place your youngster on the floor or ground on his or her side or stomach.
  • Remove any sharp things from your child’s reach.
  • Loosen any garment that is too tight.
  • To avoid injury, keep your child close to you.
  • Put nothing in your child’s mouth and don’t try to stop the seizure.

What are the treatment options available?

Pyrexia can be treated through the following methods:

  • Medications: Medications for treating pyrexia should be taken exactly as prescribed by your doctor, as excess doses can harm your liver or kidneys. Antiviral drugs are prescribed if the fever is caused by viral infections, as determined by the doctors.
  • Antibiotics: If the doctor feels that the fever is caused by bacterial infections in the bladder or gut, antibiotics are prescribed.
  • Rest: The patient should get enough sleep.
  • Fluids: To avoid dehydration, drink plenty of water and take vitamins regularly.

To prevent excessive loss of salts and minerals from the body, patients admitted with a high temperature and weakness are usually given intravenous fluids.

How do you prevent pyrexia?

By limiting your exposure to infectious diseases, you may be able to avoid contracting a fever. Here are a few pointers that can be helpful in preventing pyrexia:

  • Wash your hands frequently and encourage your children to do so as well. Show your children how to fully wash their hands by applying soap to both the front and back of each hand and rinsing well under running water
  • If you don’t have access to soap or water, keep a hand sanitizer on hand
  • Avoid touching your nose, mouth, or eyes, as these are the most common routes for viruses and germs to enter your body and infect you
  • When you cough or sneeze, cover your mouth and nose and educate your children to do the same. When coughing or sneezing, turn away from people as much as possible to avoid spreading germs

A Note from Apollo Hospitals/Apollo Group

Pyrexia is a common medical condition that affects people of all ages and is characterized by an increase in body temperature above the normal range.  By causing a fever, your immune system is attempting to eliminate the source of your illness and it generally clears up on its own within a week at the most.

Medication can be used to address this condition. The first step in determining the severity of your issue is to contact your Apollo doctor. Apollo specialists will determine the best therapy for your condition based on the diagnosis.

Call 1860-500-1066 to book an appointment

Frequently Asked Questions

What’s the difference between a fever caused by an infection and a fever caused by external conditions?

Even though both types of fever exhibit the same symptoms, the treatment administered for both would slightly vary. Fevers caused by infections may need treatment of the infection while fever caused by external factors (such as heat stress) would require the patient to stop getting exposed to the external trigger. 

How is pyrexia diagnosed?

Your Apollo doctor will begin the diagnosis by asking questions about your symptoms and medical history to determine the cause of your fever. Your doctor may:

  • Conduct a physical examination.
  • Order diagnostic tests like blood tests or a chest X-ray if needed, based on your medical history and physical assessment.
  • Because a fever in a small infant, especially one who is 28 days or younger, can suggest a dangerous illness, your baby may need hospital admission for testing and treatment.
Verified By Apollo Doctors
At Apollo, we believe that easily accessible, reliable health information can make managing health conditions an empowering experience. AskApollo Online Health Library team consists of medical experts who create curated peer-reviewed medical content that is regularly updated and is easy-to-understand.

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