Fever

Symptoms

Body temperature can vary among individuals and even at different times throughout the day. The normal body temperature is commonly considered to be 98.6°F (or 37°C). Nonetheless, a temperature of 100°F (37.8°C) and above, when measured orally with a mouth thermometer, is generally defined as a fever.

Based on the underlying cause, additional signs and symptoms associated with a fever might include:

• Sweating
• Headache
• Chills and shivering
• Muscle aches
• Irritability
• Loss of appetite
• Dehydration
• Overall weakness

How to Measure Temperature

There are many types of thermometers available that you can use to take temperature. These include oral, rectal, forehead (temporal artery), and ear (tympanic).

Rectal and oral thermometers usually provide the most precise readings of core body temperature. While ear and forehead thermometers are convenient, their measurements tend to be less accurate.

If possible, rectal temperatures in infants are considered more reliable. Be sure to provide both the measurement and the thermometer type used when informing your doctor about your temperature.

Causes

The natural body temperature involves a balance between heat production and loss. The hypothalamus, often referred to as the body's thermostat, is a region in the brain that regulates this balance. Even when in good health, body temperature can fluctuate slightly throughout the day, typically lower in the morning and rising higher by late afternoon or evening.

When the immune system detects illness, the hypothalamus raises body temperature to trigger complex processes that generate more heat and limit heat loss. For example, shivering is a mechanism the body uses to create heat. So, wrapping yourself in a blanket when feeling cold helps your body conserve heat.

Fevers lower than 104°F (40°C) associated with viral infections like the flu can assist the body’s immune system in fighting illness and are usually not dangerous.

Possible causes of fever or high body temperature include:

• Viral infections
• Bacterial infections
• Heat exhaustion
• Inflammatory disorders, like rheumatoid arthritis, which causes inflammation of the joint lining (synovium)
• Malignant (cancerous) tumours
• Certain medications, including antibiotics and drugs for high blood pressure and seizures
• Vaccinations such as those for DTaP (diphtheria, tetanus, and acellular pertussis), COVID-19, or pneumococcal disease.

Complications

Children aged six months to five years tend to be more susceptible to febrile seizures (seizures caused by fever). Approximately one-third of minors who experience a febrile seizure will likely have another, mostly within one year.

Febrile seizures can be characterised by unconsciousness, limb shaking on both sides of the body, body rigidity, and eye-rolling. While it can be frightening, most febrile seizures do not cause long-term effects.

In the event of a febrile seizure, do the following:

• Lay the child on the ground or floor on their stomach or side.
• Remove any sharp objects near the child.
• Loosen any tight clothing.
• Hold the child gently to prevent injury.
• Avoid placing anything in their mouth or attempting to stop the seizure.
• Contact 999 or emergency services if the seizure lasts longer than five minutes or if the child doesn’t recover well after the seizure.
• Seek emergency assistance or go to the hospital if this is the first seizure your child has experienced.

If emergency care isn’t necessary, consult your child’s physician promptly for further assessment.

Prevention

You can prevent or reduce the risk of fevers by minimising contact with infectious illnesses. Consider the following preventive measures:

• Receiving vaccinations as directed against infectious conditions like the flu and COVID-19.
• Adhering to public health recommendations, including wearing masks and maintaining social distance.
• Frequently washing hands and teaching children to do the same, particularly before meals, after using the toilet, after being in crowds or near sick individuals, after handling animals, and while using public transport.
• Teaching children how to wash their hands properly, ensuring they cover both sides with soap and rinse thoroughly with running water.
• Always carrying hand sanitiser for occasions when soap and water aren’t available.
• Avoiding touching the nose, eyes, and mouth, as these are common entry points for viruses and germs that cause infections.
• Covering your mouth when coughing and your nose when sneezing, and teaching your children to do the same. If possible, face away from people around you and use your elbow to cough or sneeze to prevent the spread of germs.
• Not sharing water bottles, cups, or other utensils with your children.

Diagnosis

To evaluate a fever, your doctor will likely:

• Ask about the symptoms you are experiencing and review your medical history.
• Conduct a physical examination.
• Collect throat or nasal swabs to check for respiratory infections.
• Perform any necessary tests such as blood work or a chest X-ray, depending on your physical examination and medical history.

For infants, particularly those who are two months old and younger, a fever can be a sign of a serious illness. Therefore, the baby may require hospitalisation for further tests and treatment.

Fever of Unknown Cause

When a fever persists for over three weeks (continuously or intermittently) and the cause is unclear, it is normally categorised as a fever of unknown origin. In such cases, you may be referred to a specialist in one or several medical fields for additional assessment and tests.

Treatment

To address low-grade fevers, doctors might advise against using medicine to reduce body temperature. This is because mild fevers can help combat the harmful microbes causing infection in the body. However, fevers over 102°F (38.9°C) can be uncomfortable and usually require treatment.

Non-prescription medications

If you have a high fever or feel uncomfortable, your doctor may suggest using non-prescription medications like paracetamol (Calpol) and ibuprofen (Nurofen).

It’s important to follow the dosage instructions on the label or as your provider advises. Ensure that you do not exceed the recommended doses. Prolonged use or high doses of ibuprofen or paracetamol can result in kidney or liver damage, and severe cases of overdose may also be life-threatening. Additionally, never give aspirin to children, as it can cause a rare but potentially fatal condition called Reye’s syndrome.

While these over-the-counter medications can help reduce your temperature, you might still experience a mild fever. It can take about one to two hours for the medication to take effect. If your fever does not improve after using medication, contact your provider.

Prescription medications

The doctor can recommend additional medications depending on the underlying cause of your fever. Addressing the root of your illness can help alleviate symptoms as well as the fever.

Treatment Options for Infants

Babies, particularly those under two months, may require hospitalisation for further tests and treatment. A fever in such a young child may indicate a severe infection requiring intravenous (IV) medication and continuous monitoring.

Self-Care

To ensure that you or your baby are comfortable while experiencing a fever, you can try the following self-care measures:

• Staying hydrated: Drinking plenty of fluids helps the body lose heat through the skin. The lost fluids are then replaced through sweating. Clear broths and water are good options, and infants under six months should be given breast milk or formula only.
• Resting: Generally, rest is essential for recovery. Physical activity is likely to increase body temperature.
• Keeping cool: For those who are not shivering, it’s advisable to wear light clothing, keep the room cool, and sleep with only a light blanket or sheet.

Preparing for Your Appointment

You can make an appointment with a paediatrician, family doctor, or another healthcare provider. The following information will assist you in preparing for your visit and understanding what to expect:

What to Do

• Take into account any pre-appointment instructions. When scheduling a visit, inquire if there are any specific things you should be aware of beforehand.
• Note down every detail about your fever, including when it began, where or how the temperature was taken (oral or rectal), and additional symptoms. Also, mention if you have been in contact with a sick person.
• Record all relevant personal information, including any potential contact with someone ill or a recent trip abroad.
• Write down all medications, supplements, and vitamins you or your child are taking.
• Create a list of questions to discuss with your doctor.

Some fundamental questions about fever to consider asking your doctor include:

• What could be causing the fever?
• Which types of tests are required?
• What course of treatment do you recommend?
• Is medication needed to lower the fever?
• What restrictions (if any) should I follow?

Feel free to ask any additional questions that arise during the visit.

What to Expect from Your Doctor

Be prepared to answer the following questions:

• When did you first experience your symptoms?
• How did you measure your or your child’s body temperature?
• What was the surrounding temperature like?
• Have you or your child used any fever-reducing medication?
• Do you or your child have any other symptoms? What is their severity?
• Have you or your child been diagnosed with any chronic health problems?
• What medications do you or your child take regularly?
• Have you or your child been in contact with a sick person?
• Have you or your child had surgery recently?
• Have you or your child travelled abroad recently?
• Is there anything that seems to ease the symptoms?
• Is there anything that appears to worsen the symptoms?

Being prepared with this information will help your healthcare provider diagnose and treat your fever more effectively.

When to See a Doctor

A fever alone shouldn’t be a cause for concern or a reason to see a specialist. However, there are certain situations where you need to seek medical attention for yourself or your child.

Infants and Toddlers

Fevers in infants and toddlers are particularly concerning. Therefore, it’s important to contact a physician if your baby is:

• Under three months old and has a rectal temperature of 100.4°F (38°C) or above.
• Between three to six months old with a rectal temperature above 102°F (38.9°C) or a lower body temperature but appears unusually uncomfortable, lethargic, or irritable.
• Between seven and 24 months old with a rectal temperature above 102°F (38.9°C) that persists for over a day without any other signs. Contact the healthcare provider promptly if your child has additional symptoms like a cough, runny nose, or diarrhoea.

Children

If a child develops a fever and appears alert and responsive, there’s usually no cause for alarm. This implies that your child makes eye contact, reacts to facial expressions and voices, plays actively, and drinks fluids.

However, you should contact your child’s doctor if they:

• Appear confused, lethargic, or make poor eye contact.
• Are vomiting continuously, seem irritable, or have an intense headache, stomach ache, sore throat, or other distressing symptoms.
• Develop a fever after sitting in a hot car; it’s important to seek medical attention right away.
• Have a fever that persists for over three days.
• Experience a seizure related to the fever. Dial 999 if the seizure lasts longer than five minutes or if your child isn’t recovering quickly.

Consult your child’s provider for advice in special situations, such as if they have a pre-existing condition or immune system issues.

Adults

Contact your provider if your body temperature reaches 103°F (39.4°C) or above. Also, seek medical care immediately if you experience any of the following signs along with a fever:

• Rash
• Intense headache
• Unusual sensitivity to bright light
• Neck stiffness and discomfort when bending your head forward
• Mental confusion, unusual behaviour, or slurred speech
• Repeated vomiting
• Breathing difficulties or chest pain
• Abdominal pain
• Painful urination
• Seizures or convulsions