What Is Fever? Measuring and Reducing High Fever in Babies and Children

High fever is a natural defense response of the body against infections, inflammations, or certain systemic diseases. An increase in body temperature above 37.5°C is generally considered a rise in fever. However, the meaning of fever differs for each age group. Especially in babies, high fever in children and high fever in adults should be evaluated differently.

What Is Considered a High Fever? What Is Normal Body Temperature?

Fever is a natural defense mechanism the body uses against infections or inflammatory processes. However, not every increase in temperature is considered a high fever. Normal body temperature typically ranges between 36.5°C and 37.5°C.

• 35°C or 36°C indicates low body temperature.
• 36.6°C to 36.9°C is considered normal body temperature.
• 37.0°C to 37.5°C is considered mild fever or slightly elevated temperature.
• 37.6°C to 37.9°C is often considered borderline high fever.
• 38.0°C to 38.5°C and above is considered high fever.

For example:

• 38.5°C fever in babies or adults requires medical evaluation.
• If you're wondering what should be considered a fever in adults, a body temperature between 36.5°C and 37.5°C is normal.
• A fever of 38.0°C or above in adults is classified as high fever, and the underlying cause should be investigated.

What Is High Fever? What Should Normal Body Temperature Be?

Fever is the body's natural defense mechanism developed against infections or inflammatory processes. However, not every increase in temperature means high fever. Normal body temperature generally ranges between 36.5°C and 37.5°C.

• A temperature of 35°C or 36°C indicates that the body temperature is low.
• Temperatures like 36.6°C, 36.7°C, 36.8°C, and 36.9°C are generally considered normal body temperature.
• Temperatures such as 37°C, 37.1°C, 37.2°C, 37.3°C, 37.4°C, and 37.5°C are considered mild fever.
• Measurements like 37.6°C, 37.7°C, 37.8°C, or 37.9°C are usually evaluated as borderline high fever.
• Values like 38°C, 38.1°C, 38.2°C, 38.3°C, 38.4°C, and 38.5°C indicate a high fever.
• Cases such as 38.5°C in babies, 38.5°C body temperature, or 38.5°C in adults require medical evaluation.

The answer to the question “What should the temperature be in adults?” is also related to this range.

In adults, a body temperature between 36.5°C and 37.5°C is considered normal. A temperature of 38°C or 38.5°C in adults is considered a high fever and the underlying cause should be investigated.

 

The answer to the question “What should the temperature be in adults?” is also related to this range.

Causes of High Fever

High fever can result from viral, bacterial, or inflammatory causes. The most common reasons include upper respiratory tract infections, urinary tract infections, lung infections, ear infections, and teething periods in children.

 

In some cases, a person may experience a sensation of heat or flushing without an actual rise in body temperature—this is often referred to as psychological heat. In such cases, the thermometer may show values like 36.8°C or 36.9°C, but the individual still feels hot and tense.

What Are the Symptoms of High Fever?

High fever is not limited to an increase in temperature; it usually occurs with other symptoms:

• Fatigue and tiredness
• Chills and sweating
• Headache
• Muscle and joint pain
• Increased heart rate
• Insomnia or restlessness

These symptoms become more pronounced especially around temperatures like 37.8°C, 38°C, and 38.5°C.

If a fever lasts for 3 days or more, the underlying cause should definitely be investigated.

Fever in Babies: What’s Normal, What’s Dangerous?

Babies have a more sensitive body temperature regulation system compared to adults. Therefore, even slight increases in temperature in a 1-month-old, 2-month-old, or 3-month-old baby should be monitored carefully.

• A temperature of 37°C in a baby is generally considered a mild elevation.
• However, values like 38°C or 38.5°C in a baby must definitely be evaluated by a pediatrician.
• During fever-reducing processes in 1-year-old or 2-year-old babies, fever-reducing syrup as recommended by a doctor can be used.
• Fever and diarrhea in a 1-year-old baby, or fever and diarrhea in 2-year-old babies, are usually signs of viral or bacterial infections.

Restlessness after the 1-month or 2-month vaccinations is also a common temporary reaction. During this period, mild elevations such as 37.8°C or 38°C may occur. However, if the temperature reaches 38.5°C in a baby, a doctor’s evaluation is definitely necessary. 

The most accurate way to measure body temperature in babies is rectally. Readings above 37.4°C should be closely monitored.

What Is Familial Mediterranean Fever (FMF)?

Familial Mediterranean Fever (FMF) is a genetically inherited disease characterized by periodic attacks. During these attacks, patients may experience high fever, abdominal pain, chest pain, and joint pain. In individuals with FMF, fever usually reaches levels such as 38°C, 38.5°C, or even 38.8°C in adults. Attacks typically last a few days, and if a fever persists for more than 3 days, a medical evaluation is required to consider the diagnosis of FMF.

With proper treatment, the frequency and severity of attacks can be significantly reduced.

What Helps Reduce Fever? What Is Good for Fever?

Fever is a natural defense response of the body when fighting infections. However, in cases such as 38°C fever, 38.5°C fever, or 38.8°C fever in adults, it may be necessary to reduce the fever.

So, what helps with fever?

• Plenty of fluid intake: Fever increases sweating. Therefore, fluids lost should be replaced with plenty of water, breast milk (for babies), or oral rehydration solutions.
• Adjusting room temperature: The ideal room temperature should be around 22–24°C. Overdressing should be avoided; thick clothing should be removed.
• Wiping the body with lukewarm water: Applying a cloth with lukewarm water to the body can help bring down the fever.
• Fever-reducing syrup as prescribed by a doctor: Especially during fever management in 1-year-old or 2-year-old babies, syrups containing paracetamol or ibuprofen can be used under medical supervision.
• Rest: Fatigue and energy loss can worsen the effects of fever. Adequate sleep speeds up recovery.

The answer to “What is good for fever?” depends on the person's age, the cause of the fever, and the degree of the fever. In cases of 38.5°C fever in babies, 38.5°C in adults, or fever lasting more than 3 days, medical support should be sought.

How to Measure and Reduce Fever in Babies?

Fever measurement in babies can be misleading if not done correctly. The most accurate method is rectal measurement (through the anus).

• In cases like 1-month-old baby fever, 2-month-old baby fever, or 3-month-old baby fever, values of 37.5°C and above should be closely monitored.
• A 37°C fever in babies is generally considered a mild elevation.
• However, 38°C fever or 38.5°C and above requires medical evaluation.

To reduce fever in babies:

• A fever-reducing syrup prescribed by the doctor can be used.
• The baby can be sponged with lukewarm water.
• During fever management in 1-year-old babies, avoid overdressing or wrapping the baby in blankets.
• In cases such as diarrhea and fever in 1-year-old babies or 2-year-olds, the risk of dehydration increases, so plenty of fluids should be given.

Additionally, temporary fever elevations like post-vaccination discomfort after the 1-month or 2-month vaccines may occur. In such cases, a mild rise in temperature around 37.8°C is usually seen and often subsides quickly.

The Difference Between Sudden-Onset Fever and Prolonged Fever

Sudden-onset fever is often a sign of viral infections. For example, conditions such as flu, common cold, middle ear infection, or urinary tract infection may cause a rapid temperature increase like 38°C, 38.2°C, or 38.4°C.

In contrast, prolonged fever (for example, fever lasting more than 3 days) is usually associated with bacterial infections, autoimmune diseases, or, rarely, genetic causes.

Familial Mediterranean Fever (FMF) is one example. It typically presents as 38.5°C or 38.8°C fever in adults, along with recurrent abdominal pain and joint pain during episodes.

If a 37.8°C fever persists for several days or a 38.5°C fever becomes persistent, the underlying cause should be investigated.

High Fever and Seizures: Special Attention in Children!

High fever in children should always be taken seriously because some children may experience febrile seizures during a high fever episode. This risk increases particularly with temperatures like 38.5°C in infants or 38.8°C.

The risk of seizures is most common in children between the ages of 6 months and 5 years.

If the fever rises suddenly and the child shows signs such as:

• Loss of consciousness
• Eye rolling
• Twitching or body shaking

immediate medical attention should be sought.

Things to be careful about when reducing fever:

• Fever-reducing syrup should be given at regular intervals (as advised by a doctor).
• Wiping the body with lukewarm water is recommended, but cold water should not be used.
• In cases of 38°C fever in infants or 38.5°C, fluid intake should be increased.

Fever lasting 3 days, fever lasting more than 3 days, or recurrent fever episodes must be evaluated by a pediatrician.