Understanding Fever: When to Seek Medical Attention

8 September, 2025 Doctor Pediatrician 1 category

Fever is not a standalone illness but rather a sign of an underlying issue, usually an infection.

What is a fever?

Read on for more information

What is a fever?

The body temperature naturally varies slightly throughout the day and differs based on factors like the individual, body location, and time of day. An elevated temperature above the regular range is classified as fever or pyrexia.

What temperature is a fever?

A fever is defined as a temperature of 38 degrees Celsius or higher, while anything over 37.5°C can be considered a mild fever. Fevers are common in both adults and children and may be accompanied by sweating.

Most fevers are caused by infections or other illnesses, such as the flu or a cold. Fevers are the body’s natural response to fighting off these infections. In some cases, fevers can also be caused by certain medications or heat exhaustion.

It is important to monitor a fever, especially in children, and seek medical attention if it persists or if other symptoms develop. In adults, a fever that lasts more than 3 days or is higher than 39°C should also be evaluated by a healthcare provider.

There are various ways to help reduce a fever, including staying hydrated, getting plenty of rest, and taking over-the-counter fever-reducing medications such as acetaminophen or ibuprofen. It is important to follow the recommended dosage instructions when taking these medications.

What is a normal temperature?

The average body temperature is 37°C (98.6°F), with variations occurring during the day. Armpit temperatures are slightly lower compared to oral readings.

What causes a fever?

Infections or inflammation trigger the release of specific chemicals in the body, causing fever or high temperature. The majority of fevers are a response to infections, as the elevated temperature assists in combating germs.

Fever caused by infections

Certain conditions, such as infections, common childhood illnesses like chickenpox, scarlet fever, and whooping cough, as well as infections acquired abroad, can lead to fevers. Teething, vaccinations, or overheating may also elevate a child’s temperature.

Fever caused by other conditions

Besides infections, fevers can also result from other conditions like blood clots, inflammatory responses in the body, or certain types of cancer. Fevers with unknown causes can also occur occasionally.

Read on for more details

How common is a fever?

Fever is a common occurrence in children, with some experiencing it annually. Older adults are less prone to developing fevers, but if they do, the recovery process is usually rapid.

Fevers are often a sign that the body is fighting off an infection or illness. They can be caused by a variety of factors, including bacterial or viral infections, inflammatory conditions, or exposure to extreme temperatures.

It’s important to monitor a fever and seek medical attention if it persists or is accompanied by other concerning symptoms. Over-the-counter medications can help reduce fever and discomfort, but it’s always best to consult a healthcare provider for proper diagnosis and treatment.

How do I take my temperature?

Various methods are available for measuring body temperature, with armpit and ear thermometers being commonly used. Forehead thermometers are less accurate, while rectal thermometers are no longer recommended in the UK.

It is common for parents to worry about their child’s fever, but in most cases, fevers resolve on their own without requiring treatment.

Signs of fever

Using a thermometer is the most reliable way to detect a fever, but other signs like flushed cheeks or feeling hotter than usual can also indicate elevated body temperature.

How to reduce a fever

Note: While medication like paracetamol and ibuprofen can help manage fever, they do not cure it; consistent dosages are necessary to keep the temperature in check.

Fever in adults

How do you deal with a fever in adults?

Fever, often accompanied by physical discomfort, is a natural defense mechanism against infections. While medications can lower fever, staying hydrated is essential to prevent dehydration.

Contact a healthcare provider if a fever persists for more than five days without a clear cause.

It is important to monitor your child’s temperature regularly when they have a fever. If the fever is above a certain threshold determined by your doctor, medication may be advised. It is recommended to dress your child in lightweight clothing and use a light blanket to keep them comfortable.

Cool baths or sponging with lukewarm water can also help to reduce a fever in children. Make sure to keep your child well-rested and in a cool, comfortable environment. If your child’s fever persists for more than a few days, or if they develop other concerning symptoms, it is important to seek medical attention.

When should you see a doctor about a fever?

Note: Seeking medical advice for a fever is crucial for children, especially if certain symptoms are present, such as a high fever in infants under 6 months old. Contact a doctor if accompanying symptoms persist or the fever lasts longer than five days.

When your body temperature rises above the normal range, often as a result of an infection or illness, it is considered a fever. In adults, a temperature of 100.4 degrees Fahrenheit or higher is typically considered a fever.

While mild fevers are usually not a cause for concern and can actually help the body fight off infections, you should seek medical attention if you have a fever that is persistent, accompanied by severe symptoms such as chest pain or difficulty breathing, or if it does not improve with over-the-counter medications. Additionally, if you have a weakened immune system or a pre-existing health condition, it’s important to contact your healthcare provider if you develop a fever.

What is a fever for adults?

The normal body temperature ranges between 97.7 and 99.5 degrees, and a temperature of 99.8 degrees does not necessarily indicate a fever. Fever is generally characterized by a body temperature above 100.4 degrees Fahrenheit.

Fever is the body’s natural response to infection or illness. It helps the body fight off the invading germs by stimulating the immune system. Common symptoms of fever include sweating, chills, headache, muscle aches, and fatigue.

It’s important to keep track of your body temperature when you have a fever. You can use a thermometer to monitor your temperature regularly. If your fever persists for more than a few days, or if you have other concerning symptoms, it’s best to consult a healthcare provider for further evaluation and treatment.

Causes of a fever in adults

Fever is not a disease itself but a response to combat infections or illnesses, often triggered by bacterial or viral infections. Allergic reactions may also induce fever. While medication can help manage fever, allowing the body’s immune system to fight off infections naturally is crucial.

What is considered a low-grade fever

A body temperature between 100.4 and 102.2 degrees is classified as a low-grade fever, which may not always require medication. Staying hydrated, wearing light clothing, and monitoring symptoms are essential during a fever.

In most cases, a slight fever in adults does not necessitate treatment, except in very young infants or when accompanied by concerning symptoms like confusion or difficulty eating/drinking without vomiting.

To naturally reduce fever, consider wearing light clothing, taking a lukewarm bath, and increasing fluid intake to stay hydrated. Additionally, remember that a mild fever could be a sign of a contagious illness, so practicing good hygiene is advised.

If a persistent fever is present, consider getting tested for COVID-19 or the flu, especially if temperatures exceed 102.2 degrees.

When is a fever too high?

While most fevers resolve on their own, a fever lasting more than three to five days, not responding to fever-reducing medications, or accompanied by symptoms like confusion or neck stiffness may require medical intervention.

Serious symptoms such as seizures, severe abdominal pain, or breathing difficulties may signify a medical emergency, necessitating a visit to a healthcare provider or emergency room.

How to reduce fever in adults

If your fever is due to a viral infection like a cold or flu, it will likely subside on its own. It is essential to rest, avoid close contact with others, take fever-reducing medications as prescribed, and cool down with a lukewarm bath or shower.

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About the author Katie Faley

Katie Faley is a Writing Coordinator for OSF HealthCare. She has a degree in English Studies and experience in magazine editing, digital marketing, and freelance writing.
Katie enjoys ’60s folk music, learning new skills, library visits, and spending time with loved ones.

Typically, the body temperature hovers around 37°C but can vary. Fevers, starting at 38°C, indicate elevated temperatures. Fevers above 39°C are categorized as high fevers, best measured with a thermometer.

Fever often accompanies cold or flu viruses, making individuals feel unwell, whether hot and sweaty or cold and clammy.

This page focuses on fevers in adults; for information on children, refer to related content.

Video: Fever in adults

Note: This video does not cover fever in children.

(Healthify He Puna Waiora, NZ, 2025)

Looking after yourself when fever strikes

Most fevers resolve within 3 to 5 days with home care, including staying hydrated, resting, dressing lightly, and maintaining good hygiene.

Stay hydrated with water or rehydration fluids.
Avoid alcohol to prevent dehydration.
Rest and avoid drafty areas.
Wear light, comfortable clothing.
Use a cool cloth for comfort.
Change clothing and bedding if sweaty.

When to seek help

Although most fevers are not concerning, seek medical advice if fever persists, worsens, or presents with alarming symptoms.

Special consideration for older adults without fever but acting ill should prompt medical attention.

When to contact a healthcare provider or call Healthline 0800 611 116 for advice

If your symptoms worsen or persist, or if you have specific underlying conditions, seek medical advice promptly.

Dark urine, worsening symptoms, and uncontrollable shivering
Unusual headaches, breathing issues, or confusion
Recent travel history or immune-compromising conditions

Call 111 or visit the ER if:

In an emergency situation, such as hallucinations, seizures, or severe symptoms like vomiting or difficulty breathing, seek immediate medical attention.

Understanding Fever and Treatment Options

Fever, typically a response to infection, can also result from other causes like allergies, drug reactions, or inflammatory conditions. Treatments may vary depending on the underlying cause.

healthdirect Australia offers free access to medical professionals for guidance on managing fever.

If your baby under 3 months has a fever above 38°C, seek urgent medical help.

Key facts

Fever is part of the body’s immune response, often caused by infection.
A fever can lead to high body temperature, sweating, and chills.
Monitoring fever with a thermometer is crucial.
Rest, hydration, and coolness help manage fevers.
Seek medical attention for severe symptoms.

What is a fever?

Fever occurs when body temperature exceeds normal levels, known as ‘having a temperature.’ Check your temperature with a thermometer and seek care if it rises above 38℃.

Your temperature varies based on factors like age, activity, and time of day.

Fever is diagnosed via temperature measurement using a thermometer.

touchless forehead thermometers
in the ear
under the armpit
under the tongue
in the rectum

Ensure the thermometer is clean and follow the manufacturer’s instructions.

If caring for a child with a fever, refer to Fever in children.

Additional information:

Common symptoms accompanying a fever include chills, sweating, headache, muscle aches, and weakness.

Fever is the body’s natural response to infections, illnesses, or other medical conditions. It helps the body fight off pathogens and can be a sign that the immune system is working to protect you.

If your fever persists for more than a few days, or if you experience severe symptoms such as difficulty breathing, chest pain, or confusion, seek medical attention immediately.

What symptoms are related to a fever?

Fever is indicated by a high temperature, usually above 38℃, accompanied by symptoms like sweating, chills, shivering, and body aches.

What causes a fever?

Fever is the body’s natural response to infections caused by viruses or bacteria.

To check your symptoms, use the Symptom Checker tool.

Additional information that can help diagnose the cause of a fever includes:

Recent exposure to sick individuals
Any chronic medical conditions
Medications being taken
Any recent infections

Tests that may be conducted to determine the cause of a fever include blood tests, urine tests, imaging studies, and cultures of bodily fluids.

When should I see my doctor?

If a baby under 3 months old has a fever higher than 38℃, seek immediate medical attention.

Consult a doctor if the fever persists for more than three days or if other concerning symptoms develop.

When to seek urgent care

Adults experiencing fever with severe symptoms such as headache, vomiting, or difficulty breathing should go to the emergency department.

Children with fever and specific symptoms require immediate medical attention.

When to seek medical attention

If the fever persists for more than a few days, or if it is accompanied by other severe symptoms such as difficulty breathing, chest pain, confusion, or severe headache, it is important to seek medical attention immediately. These could be signs of a more serious underlying condition.

Other methods to reduce fever

In addition to staying hydrated and getting rest, there are other methods that can help reduce fever. Applying a cool, damp cloth to the forehead, taking a lukewarm bath, or using a fan can help bring down the body temperature. It is also important to monitor the fever and keep track of any changes in symptoms.

Preventing fever

While it is not always possible to prevent fever, there are steps that can be taken to reduce the risk of getting sick. Practicing good hygiene, such as washing hands regularly, getting vaccinated, and avoiding close contact with people who are sick, can help prevent the spread of illnesses that may cause fever.

Can fevers be prevented?

Fevers are part of the body’s immune response and should be addressed with medical attention if they are persistent or severe.

While fevers themselves cannot always be prevented, there are some steps you can take to help reduce your risk of getting sick and developing a fever:

Wash your hands regularly with soap and water to prevent the spread of germs.
Avoid close contact with people who are sick to minimize your exposure to illness.
Practice good hygiene by covering your mouth and nose when you cough or sneeze.
Get vaccinated against common illnesses to protect yourself and others.
Maintain a healthy lifestyle with regular exercise, balanced diet, and adequate sleep to keep your immune system strong.

Complications of fever

Febrile convulsions in children occur due to rapid spikes in temperature and typically do not have long-term consequences.

Resources and support

If you have concerns about your symptoms, contact the healthdirect helpline for assistance.

Sources:

Last reviewed: March 2024

Search our site for

Types of thermometers
Medications for fever

Need more information?

Find more information on this topic from trusted partners.

Fever and high temperature: kids and teens | Raising Children Network

If a child’s temperature goes above 38℃, take appropriate measures.

Fever in Children – Rahma Health

Fever is characterized by a temperature above 38°C.

Fever – Better Health Channel

A mild fever up to 39°C can actually help the immune system fight infections.

Fever in babies

Discover how to manage a baby’s fever and the normal temperature ranges.

Fever in babies and children – infographic

Tips for managing a child’s fever and knowing when to seek medical help.

Fever | Children’s Health Queensland

Understand the causes, treatments, and when to seek help for a fever.

Fever factsheet | The Sydney Children’s Hospitals Network

Fever is the body’s way of responding to illness and infection.

Febrile convulsion factsheet | The Sydney Children’s Hospitals Network

Febrile convulsions can happen in children due to high fevers.

Hypothermia: Reversible Causes of Cardiac Arrest | Ausmed

Learn about hypothermia and its causes on the Ausmed Education website.

Disclaimer

Healthdirect Australia does not take responsibility for the content of external websites.

Infographic on fever in babies and children
Information on fever in children

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Types of thermometers
Medications for fever

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Category: About child care