Are fevers good for adults?

Table of Contents

What is a fever?

A fever is a temporary increase in your body temperature, often due to an illness. It’s a common sign that your body is fighting an infection. Fevers help activate your immune system and can destroy viruses and bacteria. A normal body temperature is typically around 98.6°F (37°C). A fever is generally defined as a temperature above 100.4°F (38°C). Fevers are most often caused by:

Viral or bacterial infections, such as the flu, pneumonia, or urinary tract infections

Inflammation, like with arthritis
Heat-related illnesses, like heat stroke
Certain medications or vaccinations

Some cancers, especially in children

Fevers are typically harmless. But sometimes a very high fever can be serious, especially in infants, young children, older adults, and people with weakened immune systems. Call your doctor if you have any of these symptoms along with a fever:

Confusion

Stiff neck
Difficulty breathing
Seizures

Rash

How fevers work

When you have an infection, your immune system releases proteins called pyrogens into your blood. Pyrogens travel to your brain and raise your body’s thermostat. This kicks your body into fever mode:

Your blood vessels constrict to conserve heat.

You start shivering as your muscles contract to generate more heat.
Your body stops sweating since evaporating sweat cools you down.

Once your temperature hits around 101°F (38.3°C) or higher, the hypothalamus – the body’s thermostat – will work to lower your fever. It does this by:

Dilating blood vessels to increase blood flow and release heat.
Restarting sweating to allow evaporative cooling.
Slowing metabolic processes that generate heat.

This fever process helps create an environment where your immune system is better able to kill viruses and bacteria. Most fevers from infection last 3 to 5 days.

Are fevers good or bad?

Most doctors agree that fevers below 102°F (39°C) are beneficial and help fight infection. Moderate fevers stimulate the immune system and speed up your body’s defenses. Some studies show that fever helps:

Activate white blood cells to attack invading bacteria and viruses.

Increase the production of antibodies and interferon, which fight viruses.
Enhance neutrophil activity against bacteria.
Boost T-lymphocyte activity to kill infected cells.

Interfere with the metabolism and replication of bacteria and viruses.
Trigger the release of iron, which bacteria need.
Inactivate certain heat-sensitive bacterial toxins and viruses.

So in most cases, a fever is helpful and a sign your body is fighting an infection optimally. Fevers generally don’t need treatment unless they are causing discomfort or reach high levels.

However, a prolonged high fever over 104°F (40°C) can be dangerous. Risks include:

Febrile seizures. About 2-5% of children 6 months to 5 years may have a seizure with a rapid high fever.

Heat exhaustion and heat stroke. This can occur if a fever is uncontrolled and raises your body temperature too high.
Delirium or hallucinations, especially in the elderly.
Rare cases of brain damage from temperatures over 107-108°F (42°C).

So while most fevers are beneficial, extremely high fevers do need medical attention to bring the temperature down and prevent complications.

How to treat a fever

For most adults, you can treat a fever at home with the following methods:

Rest. Don’t overexert yourself so your body can direct energy towards fighting infection.

Stay hydrated. Drink extra water, juices, or electrolyte beverages.
Light clothing. Dress lightly in breathable fabrics to release heat.
Cool towels. Place a cool, damp washcloth on your forehead, wrists, armpits, and neck.

Lukewarm bath. Soak in a tub of lukewarm water to lower body temperature.
OTC medications like acetaminophen or ibuprofen to relieve discomfort.
Avoid vigorous exercise and alcohol which can worsen dehydration.

You should contact your doctor if your temperature is over 103°F (39.4°C) for more than 3 days or any fever over 104°F. They may prescribe fever-reducing medications or rule out serious illness. Seek immediate care for any of these red flag symptoms:

Fever above 105°F (40.5°C)
Confusion, delirium, or loss of consciousness

Seizures
Severe dehydration
Fever in a newborn, infant, elderly, or immunocompromised person

Fever that lasts longer than 5 days in adults or 3 days in children

These may indicate a serious underlying infection or risk of complications that require prompt medical care.

Risk factors for high fevers

While moderate fevers boost immunity, some people are at higher risk of developing an overly high or prolonged fever that can be dangerous. Risk factors include:

Infants under 3 months old – Their immune systems are still developing.
Elderly adults over 65 years old – Their immune function declines with age.
Pregnant women – Change in immune function plus risk of dehydration and heat stroke.

Chronic medical conditions – Like diabetes, heart disease, lung disease.
Weakened immune system – Due to illness like cancer or HIV/AIDS.
Taking certain medications – Such as antibiotics, anti-seizure, anti-psychotics.

Genetic disorders – Such as Kostmann disease which impairs neutrophil function.

In these groups, even a mild fever can rapidly spike to dangerous levels. They will need careful monitoring and quicker treatment with fever reducers, fluids, and cooling methods.

Age	Temperature (F)	Temperature (C)
Newborn to 3 months	100.4	38
3-6 months	101	38.3
6-24 months	102	38.9
2-5 years	102.2	39
5 years and older	103	39.4

Recommended temperature limits by age when to seek medical care

This table summarizes when to call your doctor based on a fever and the person’s age:

For newborns up to 3 months old, seek care for any fever of 100.4°F (38°C) or higher.
For babies and toddlers 3-24 months old, call for fevers over 102°F (38.9°C).

For children 2-5 years old, contact your doctor for temperatures above 102.2°F (39°C).
For older children and adults, seek medical care for fevers exceeding 103°F (39.4°C).

Younger infants and children tend to be at higher risk for seizures, dehydration, and other complications with their still-developing immune systems and small bodies. So they require lower fever thresholds before calling your pediatrician.

Conclusion

In most cases, low-grade fevers below 102°F (39°C) are helpful to fight infection and activate the immune system. Higher prolonged fevers can be more dangerous and require treatment to avoid complications like brain damage or seizures. Stay hydrated, rest, and use fever reducers if needed. But contact your doctor promptly for any fever over 103°F or a fever lasting more than 3 days in adults or children. Pay close attention to symptoms in infants, elderly adults, pregnant women, and other high-risk groups and call for care with any fever over 100°F. With proper monitoring and treatment, most fevers are temporary and beneficial reactions as your body heals itself.