Hyperpyrexia – Causes, Symptoms, Treatment

Learn From Doctor Team
Learn From Doctor Team is made up of well-qualified doctors of different fields with brilliant academic results and professional careers. The article is written and reviewed by doctors of this specialty.

Hyperpyrexia Overview

Hyperpyrexia occurs when the body temperature rises to 106°F (41.1°C) as a result of a fever. The average body temperature is 98.6°F (37°C).

Even so, minor changes occur during the day. Your core temperature, for instance, is minimum in the early morning and maximum in the late afternoon.

When the body temperature increases a few points above average, you seem to have a fever. This is usually described as a temperature of 100.4°F (38°C) or above.

Apart from fever, the body temperature will rise significantly above its reasonable level in some situations. This is known as hyperthermia.


What Happens in Hyperpyrexia

The brain instructs the body to increase its baseline temperature above average in hyperpyrexia as well as many other cases of fever. In response to the brain’s signals, the body increases its temperature to a base point. This response is typically triggered by an infection or trauma.

Hyperpyrexia is different from Hyperthermia, which is a medical term for an uncontrolled increase in core temperature caused by an excess of body heat.

The brain does not regulate the increase in temperature in hyperthermia as it does in most fevers. Instead, the body cannot withstand the heat caused by environmental factors, causing it to overheat.

Heatstroke is caused by hyperthermia rather than hyperpyrexia.

Signs and Symptoms

The principle sign is the body temperature 106° degrees Fahrenheit(41.1° degrees Celcius) or above.

There can be some additional symptoms such as;

  • Arrhythmia – irregular heartbeat
  • Muscular spasms
  • Rapid breathing
  • Seizure
  • Confusion and dizziness
  • Headache
  • Unconscious
  • Coma
  • Intense thirst
  • Sweating
  • Nausea
  • Contracted pupil
  • Vomiting
  • Stomach cramps
  • Hot and redness of the skin

Hyperpyrexia is classified as a medical emergency. Organ damage and death can occur if untreated. Seek emergency medical services at all times.

Causes of Hyperpyrexia

In most cases, hyperpyrexia is caused by a viral or bacterial infection. Among the other reasons may include:


Hyperpyrexia can be caused by a variety of serious bacterial, viral, and parasitic infections.

Amongst them the most commons are;

  1. Bacterial infections caused by S. pneumoniae, S. aureus, and H. influenzae
  2. The enterovirus and influenza A viral infections
  3. Malarial parasitic infection

Hyperpyrexia can also be caused by sepsis. Sepsis is a potentially fatal infection complication. In sepsis, the body releases a number of compounds into your bloodstream to aid in the battle against infection. This may sometimes result in a severe inflammatory reaction, which can lead to organ damage and failure.

Your doctor will take a sample to screen for the existence of microorganisms in order to detect an infectious cause of hyperpyrexia. This sample may be a blood sample, urine sample, stool sample, or sputum sample, depending on the type of the suspected infection. The infectious agent can then be identified by your doctor using different culture or molecular methods.


Sepsis can cause hyperpyrexia in rare instances. Sepsis is a potentially fatal reaction to an infection caused by the immune system. The overpowering immune system reaction enters the bloodstream, potentially causing organ damage or total failure.


In rare cases, exposure to such anesthetic medications can result in exceptionally high body temperatures. This is known as malignant hyperthermia (sometimes called malignant hyperpyrexia).

Malignant hyperthermia is inherited, which means it can be passed on from parent to child.

A sample of muscle tissue may be used to diagnose malignant hyperthermia. If you have a family member that has malignant hyperpyrexia, you should consider getting screened.

Effects of Certain Drugs

Aside from anesthesia medications, the use of some prescription drugs may result in conditions with hyperpyrexia as a symptom.

Serotonin syndrome is an example of such a disorder. Serotonergic medications, such as selective serotonin reuptake inhibitors, may cause this potentially fatal condition (SSRIs).

Another example is a neuroleptic malignant syndrome, which may result from an antipsychotic drug reaction.

Furthermore, some recreational drugs, such as MDMA (ecstasy), can induce hyperpyrexia.

Symptoms of these conditions usually appear soon after exposure to the medication.

To detect opioid-related hyperpyrexia, the doctor will conduct a physical exam and review your history of drug exposure.


Heatstroke occurs when the body overheats to dangerously high temperatures. Overexertion in a hot environment will result in this. Heatstroke can also occur in people who have trouble controlling their body temperature. This may include elderly people, very young children, or people suffering from chronic illnesses.

To diagnose heat stroke, the doctor will conduct a physical examination. They can also measure kidney function because heatstroke and dehydration can stress the kidneys.

Other Causes

Thyroid storm is a rare disorder that occurs when thyroid hormones are released in excess.

Thyroid storms must be identified and treated as soon as possible. Your doctor will confirm thyroid storm based on your medical history, symptoms, and lab tests.


Hyperpyrexia in Children

Hyperpyrexia may be caused by Kawasaki syndrome or illness, which is more common in infants. Kawasaki syndrome is characterized by inflammation of the body’s medium-sized arteries. High fever is one symptom of Kawasaki disease, which can lead to hyperpyrexia if left untreated.

Sponging may help to reduce body temperature in hyperpyrexia
Sponging may help to reduce body temperature in hyperpyrexia

Hyperpyrexia in Infants

In babies, hyperpyrexia is uncommon. A newborn with hyperpyrexia, on the other hand, could be at risk of a severe bacterial infection.

Some scientists and health professionals believe there is a connection between high fever and the risk of severe bacterial infection in very young infants.

If your baby is under 3 months old and has a fever of 100.4°F or higher, it is important that they seek medical care right away.

Seek emergency care if your baby shows signs of hyperpyrexia
Seek emergency care if your baby shows signs of hyperpyrexia

Diagnosis of Hyperpyrexia

A thermometer is used to diagnose hyperpyrexia. If the temperature rises above 106.1°F, the individual is suffering from hyperpyrexia.

Since hyperpyrexia is not a disease in and of itself, but rather a symptom of a greater issue, determining the underlying cause of the high fever is more important and therefore more difficult.

A doctor will examine the patient and perform tests to rule out the more common causes of high fever. These tests can consist of the following:

  • Blood tests to look for signs of infection
  • Brain imaging tests to look for intracranial hemorrhage

The results of any further tests would be heavily influenced by the person’s other symptoms.


Treatment Procedure

Treatment for hyperpyrexia entails treating both the rise in body temperature and the underlying disease.

Sponging or swimming in cold water will help you cool down. Using ice packs, blowing cold air, or spraying with cool water can also be beneficial. In addition, any clothing that is too tight or too bulky should be omitted. When you have a fever, these steps may not be effective in lowering the temperature to normal, or even by a degree or two.

As a supportive medication and to aid with dehydration, you may also be given intravenous (IV) fluids.

Your doctor will determine the cause of the hyperpyrexia if it is caused by an infection. They would then treat it with the appropriate drug therapy.

If you have malignant hyperthermia, the doctor or anesthesiologist will discontinue all anesthetic medications and administer dantrolene. You should still remind your doctor or anesthesiologist of your condition in the future.

Drug-related hyperpyrexia is managed by stopping the drug, getting supportive treatment, and treating symptoms such as rapid heart rate and high blood pressure.

Antithyroid medications can be used to treat conditions such as thyroid storms.


Signs of Emergency

  • When body temperature is above 100°F in 3-month-old infants
  • Irregular breathing or heartbeat
  • Seizure
  • Confusion
  • Headache
  • Rash on skin
  • Severe vomiting
  • Severe diarrhoea
  • Abdominal pain
Hyperpyrexia is a medical emergency
Hyperpyrexia is a medical emergency

Hyperpyrexia in Covid-19 Patients

COVID-19 is often associated with hyperpyrexia. However, not everyone infected with COVID-19 develops a fever. Cough, nausea, and loss of smell or taste are some other typical symptoms.

The Centers for Disease Control and Prevention provided this data.

Fever elevates the body’s temperature above normal levels. This is a normal part of the immune system’s response to infection.

Many infections can cause fever, but if a person’s temperature is 100.4°F (38°C) or higher, they should remain at home and seek medical attention. This is due to the possibility that the fever is an early symptom of COVID-19.


Clinical Introduction(For Health Professionals)

Coronavirus disease 2019 (COVID19), caused by the extreme acute respiratory syndrome coronavirus 2 (SARSCoV2), has shaken global health systems, infecting over 5 million people and killing nearly 400 000. COVID19 clinical courses range from asymptomatic to multiorgan failure and death. Despite enormous efforts in COVID19 studies, the mechanisms underlying disease progression remain unknown. Several clinical predictors of SARSCoV2 infection have been established, including some comorbidities, hypoxia, elevated inflammatory markers, and acute kidney injury.

Hyperpyrexia is characterized as a rise in core body temperature (BT) above 106.7°F (41.5°C) in order to reach an abnormally elevated hypothalamic thermoregulatory threshold, as compared to hyperthermia, which is defined as an increase in core BT that exceeds the normal hypothalamic thermoregulatory limit. Brain dysfunction is the most common cause of hyperpyrexia, while infection and sepsis are considered to be uncommon causes. The impact of hyperpyrexia on infectious disease patients is conflicting. Hyperpyrexia may have a negative effect on survival in patients with bacterial infections, but it may not have a negative impact on mortality in patients with viral illnesses.

Clinical Discussion(For Health Professionals)

Extremely high calculated core BT is a catastrophic condition that necessitates immediate treatment and identification of the underlying causes. High fever causes direct cellular damage and exacerbates inflammatory responses, so cooling measures should be introduced as soon as possible. Furthermore, the causes of highly elevated BT must be identified since many etiologies will result in death even though the fever symptom is under control. It is important to distinguish whether the high BT is caused by hyperpyrexia or hyperthermia since the etiologies of these two conditions are distinct. The pathology of hyperpyrexia is centrally directed, resulting in a reset of hypothalamic control to a higher degree, while hyperthermia is typically caused by peripheral etiologies that result in excessive heat output or defective heat loss.

There is no published literature in COVID19 that explains the pathophysiology of hyperpyrexia. There may be three underlying mechanisms;

  • SARSCoV2 caused direct brain damage.
  • persistent immune dysfunction and cytokine dysregulation
  • thrombosis of the blood vessels

To gain cellular entry into human organs, SARSCoV2 binds angiotensin-converting enzyme 2 (ACE2) receptors. ACE2 receptors are strongly expressed in airway epithelia, lung parenchyma, and GI epithelia, which explains why dyspnea, cough, and GI complaints are the most common symptoms in COVID patients19. Recent evidence suggests that ACE2 receptors are expressed in neurons, astrocytes, and oligodendrocytes in a complex spatial localization pattern. The direct invasion of SARSCoV2 into nervous systems could explain COVID19related neurological problems such as stroke, encephalitis, and encephalopathy.

Always wear mask to prevent covid-19 hyperpyrexia
Always wear mask to prevent covid-19 hyperpyrexia

SARSCoV2 invasion can cause hyperpyrexia through two distinct mechanisms: direct injury to neurons in hypothalamic thermoregulatory pathways and injury to other parts of the brain resulting in the local development of proinflammatory and pyrogenic cytokines. The absence of a natural circadian rhythm and the occurrence of hypothermia are pathognomonic symptoms of brain injury-induced hyperpyrexia.

SARSCoV2 may injure the brainstem respiratory core, which explains why patients with COVID19 often report less dyspnea than the actual degree of hypoxia and the extent of lung pathology. Some patients demonstrated a disparity between the degree of COVID19 pneumonia development, as evidenced by a decrease in oxygen demand and improved pulmonary mechanics, and the degree of respiratory function compromise, as evidenced by the absence of spontaneous breathing despite sedation vacation. This adds to the evidence that SARSCoV2 can cause brain damage.

Furthermore, our case series showed a strikingly high incidence of changing mental state (66.7 percent) as a presenting complaint, implying that many patients had encephalopathy prior to admission. The encephalopathy’s early-onset (median 2 days [range, 17 days]) increases the likelihood that it was triggered by SARSCoV2’s direct neuroinvasion rather than its indirect influence from toxic metabolic encephalopathy.

SARSCoV2 causes a distinct pattern of immune dysfunction characterized by defective antigen presentation and lymphoid cells, but preserved monocytes secrete tumor necrosis factor (TNF) and interleukin6 (IL6). Serum levels of proinflammatory cytokines (TNF, IL1, and IL6) and chemokines (IL8) are significantly higher in patients with extreme COVID19 than in individuals with moderate disease. 17 IL6 can also be used as a predictor of SARSCoV2 disease progression. 18 Endogenous pyrogens include IL1, IL6, and IL8. 19 When cytokines expression in malaria patients with and without hyperpyrexia was compared, it was discovered that IL6 was significantly higher in the hyperpyrexia population. 20 Thus, elevated IL6 levels may be associated with hyperpyrexia in COVID patients19.

COVID19 patients are at an elevated risk of arterial and venous thrombosis. SARSCoV2 has the ability to directly kill vascular endothelial cells and cause uncontrolled inflammatory responses, which can lead to systemic thrombosis and generalized coagulopathy. The development of a hematoma is a well-known but rare cause of hyperpyrexia. While this is the least possible explanation in our cases, it should be considered for certain patients who experienced an eightfold rise in DD and a sudden increase in oxygen demand while hospitalized. Furthermore, some patients are the only ones who have survived more than 24 hours after the onset of hyperpyrexia, suggesting a distinct etiology for her extraordinarily high BT.

The consequence of Hyperpyrexia in Covid-19 Patients

Unfortunately, patients with COVID19 who experience hyperpyrexia have a 100%(hundred percent) mortality rate. In COVID patients, hyperpyrexia can mean poor clinical outcomes and worsen mortality19. The underlying causes of COVID19 hyperpyrexia are unclear, but it may be due to SARSCoV2related brain damage, an exuberant immune response, or thrombus formation.


Hyperpyrexia Summary

A temperature of 106°F or higher is considered a medical emergency. If the fever is not brought down, organ damage and death may occur.

In fact, if you have a fever of 103°F or higher, along with other severe symptoms, you should seek urgent medical attention.

Your doctor will work rapidly to determine the source of your high fever. They’ll work to get the fever down safely until any major problems arise.

Last Updated on February 23, 2022 by Learn From Doctor Team

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