For most people, most of the time, a fever isn’t dangerous enough to cause brain damage. This may go against what you’ve been taught.
It helps to know what causes a fever, what the potential complications can be, and when to call your healthcare provider or head to the emergency room. It’s also important to know what’s different about fevers in kids versus adults.
This article will discuss fevers and how you know when one is too high. It will also talk about what you should do if you have a low or high fever.
Why You Get Fevers
Usually, fevers are a good thing. They’re one of the ways your body naturally fights off infections.
A part of the brain called the hypothalamus acts as a thermostat for your body. Most of the time, it keeps body temperatures around 98.6 degrees. When you get sick, though, the hypothalamus raises the temperature to make it hard for germs to live and multiply in the body.
It’s great when a fever fights against the germs in your body. But it’s not so great when the fever gets so high that it could harm you.
Causes of a Fever
A lot of things can cause high fevers. Some of the causes typically begin with low-grade fevers that can turn into high-grade ones, such as:
VirusesBacteriaFungiToxinsDrugs
If you don’t receive treatment for your fever or your body doesn’t respond to treatment, the fever can become dangerous.
Some medical conditions are associated with high-grade fever. These medical conditions include:
Intracranial hemorrhage (bleeding inside the brain) Thyroid storm Serotonin syndrome Sepsis Kawasaki syndrome Neuroleptic malignant syndrome Heatstroke Drug overdose
Symptoms and Complications of a Fever
As your fever rises, it may cause new symptoms.
Low-grade fever (pyrexia) symptoms include:
Chills Sweats Feeling hot Headache Eyes that are achy or tired Thirst Low appetite
Early high-grade fever symptoms may still include those from the list above, plus:
Extreme sweating Dizziness and light-headedness Muscle cramps Fatigue Weakness Nausea
Persistent or worsening high-grade fever can also cause:
Contracted (small) pupilsMild confusionCool, moist, pale skinUpset stomach or vomitingDecreased urine or inability to urinate
Longer-lasting high-grade fever or temperatures above 106.1 F can lead to:
Extreme confusion Hallucinations Loss of consciousness Shallow, rapid breathing Hot, dry, red skin Weak, fast heartbeat Dilated (large) pupils Seizures
Brain Damage and Death
While high fevers, especially those that last a long time, can lead to brain damage and death, this is extremely rare. Brain damage can occur if a fever goes above 107.6.
According to a 2016 study, heatstroke is the most deadly heat-related illness. It kills 58% or more of the people it affects. Among survivors, most make full recoveries. But some may have long-term organ damage.
Organs that can be damaged by a prolonged high fever include:
BrainHeart and cardiovascular systemKidneysLiverIntestines
Proper treatment is the key to preventing severe complications of high-grade fevers.
Treatment of a Fever
If someone has a fever but feels fine for the most part, treatment isn’t necessary. In fact, because the fever’s job is to help kill an infection, treating a low-grade fever can interfere with the body’s efforts to fight germs.
When it comes to children who have a fever, a rule of thumb is that if they’re playing and have energy, there’s no immediate danger.
When fever-related symptoms are making you feel lousy or the temperature has crept up near that 103–104 degree mark, an over-the-counter fever-reducing medication like Tylenol (acetaminophen) or Motrin/Advil (ibuprofen) can help you feel better.
These medications provide only temporary results. They work for four to eight hours and then wear off. This means your fever may come back, and you’ll need to take more. This doesn’t mean something is wrong or that it didn’t work.
Rest and plenty of liquids can help your body fight against the fever and underlying illness as well.
Other home remedies may help, but you need to know which ones are safe and effective. You also need to know which ones are potentially harmful. Talk to your healthcare provider to learn which home remedies are best.
Treatment by Temperature
For most adults and older children, looking at the symptoms more than the number on the thermometer can help you determine if there’s a serious health issue. Still, it’s good to keep an eye on how high the fever gets.
Fever in very young children can be a sign that something is seriously wrong, so it shouldn’t be ignored. Your pediatrician should have an on-call number so you can get advice at any time. In some cases, you may want to go straight to the emergency room.
If your fever doesn’t go away or you have additional symptoms that show you have an illness, you should see a healthcare provider.
If you go to your healthcare provider’s office, urgent care, or the ER for fever treatment, you can expect medications and testing to figure out what’s causing the elevated temperature.
Summary
A fever is one way your body naturally fights against infections. High fevers are 103 degrees or above. A potentially dangerous fever begins when your temperature is at least 104 degrees. If you have a fever that is 105 degrees or higher, you need immediate medical attention.
A Word From Verywell
Adults are usually able to determine when our symptoms are making us feel so bad that we need to seek medical treatment. But if you aren’t sure, learn how to check your cold and flu symptoms, evaluate a fever, and know the situations when you should see a healthcare provider for a fever.
Correction -March 14, 2022: This article was updated to remove reference to hyperpyrexia.
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