Cold & Flu Symptoms When Is a Fever Too High? And what should you do about it? By Kristina Duda, RN facebook twitter linkedin Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention. Learn about our editorial process Kristina Duda, RN Medically reviewed by Medically reviewed by Michael Menna, DO on January 07, 2020 Michael Menna, DO, is a board-certified, active attending emergency medicine physician at White Plains Hospital in White Plains, New York. Learn about our Medical Review Board Michael Menna, DO on January 07, 2020 Print Table of Contents View All Why You Get Fevers Causes Symptoms/Complications Treatment High-grade fevers, called hyperpyrexia, involve temperatures above 103 degrees and can be dangerous. However, when gauging a fever's danger in yourself or your child, it's more complicated than just looking at a number—especially in children. For most people, most of the time, a fever isn't dangerous in terms of causing brain damage. This may go against what you've been taught to fear. It helps to know what causes a fever, what the potential complications can be, and when to call your doctor or head to the emergency room. It's also important to know what's different about fevers in kids versus adults. Why You Get Fevers Usually, fevers are actually a good thing. They're part of the natural way the body 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 (37 degrees Celsius). When you get sick, though, it raises the temperature to make it hard for germs to live and multiply. That's all well and good, unless the fever gets so high that it could start harming you. Causes A lot of things can cause high fevers. Some include low-grade fevers that become high-grade, such as: VirusesBacteriaFungiToxinsDrugs If a fever continues unchecked, or your body doesn't respond to treatment, the fever may rise into the danger zone. Verywell / Jiaqi Zhou Some medical conditions that don't involve low fevers are associated with high-grade fever. Some of these are: Intracranial hemorrhageThyroid stormSerotonin syndromeSepsisKawasaki syndromeNeuroleptic malignant syndromeHeatstrokeDrug overdose Symptoms and Complications As your fever rises, it may bring on new symptoms. Low-grade fever (pyrexia) symptoms include: ChillsSweatsFeeling hotHeadacheEyes that are achy or tiredThirstLow appetite Early high-grade fever (hyperpyrexia) symptoms may still include those from the list above, plus: Extreme sweatingDizziness and light-headednessMuscle crampsFatigueWeaknessNausea 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 confusionHallucinationsLoss of consciousnessShallow, rapid breathingHot, dry, red skinWeak, fast heartbeatDilated (large) pupilsSeizures Fevers over 106.1 F (41.2 C) need medical attention to prevent serious, long-term consequences—including brain damage and death. Brain Damage and Death While high fevers, especially those that are prolonged, can lead to brain damage and death, this is extremely rare. According to a 2016 study, heatstroke is the most deadly heat-related illness, killing 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 prolonged hyperpyrexia include: BrainHeart and cardiovascular systemKidneysLiverIntestines Proper treatment is the key to preventing severe complications of high-grade fevers. Treatment 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 kill infectious agents, treating a low-grade fever can interfere with the body's efforts. When it comes to children, 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 F mark, an over-the-counter fever-reducing medication like Tylenol (acetaminophen) or Motrin/Advil (ibuprofen) can help you feel better. The effects of these medications are only temporary, though. They work for 4 to 8 hours and then wear off, meaning 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. Children and teenagers should not be given aspirin for a fever due to the risk of Reye syndrome, a rare and serious illnesses that causes brain and liver damage. Rest and plenty of liquids can help your body weather the fever (and underlying illness), as well. Other home remedies may help, but you need to know which ones are safe and effective, and which ones are potentially harmful. Safe (and Not) Fever Home Remedies Treatment by Temperature For most adults and older children, symptoms are a better indicator of when it's a problem than the number on the thermometer. Still, it's good to keep an eye on how high the fever gets. Adults and Children 4+ Temperatures Fahrenheit Celsius High-Grade 103 39.4 Potentially Dangerous 104 40 Get Medical Attention 106.7 and up 41.5 With children under 3 years of age, and especially with babies, it pays to be more cautious and know what the exact temperature is. Fever in very young children can be a sign that something serious is wrong, so it shouldn't be ignored. Your pediatrician should have an on-call number so you can get advice at any time, or, in some cases, you may want to go straight to the emergency room. Babies and Toddlers Temperatures by Age Fahrenheit Celsius What to Do 0-3 Months 100 oral, 100.4 rectal 37.7 oral, 38 rectal Call doctor or go to ER 3 Mo.-3 Years 102.2 39 Call doctor for advice, even after hours Medical Care If your fever is caused by an infection, it won't go away until the infection is gone or at least improves. Depending on the specific pathogen, this may require medical treatment. If your fever doesn't go away or is accompanied by other symptoms that suggest illness, you should see a doctor. If you rush to your doctor'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. A Word From Verywell Adults are typically better 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, evaluate what is going on. Learn how to check your cold and flu symptoms, evaluate a fever, and know the situations when you should see a doctor for a fever. Signs Your Fever Might Be Serious Was this page helpful? Thanks for your feedback! Looking to avoid getting the flu? Our free guide has everything you need to stay healthy this season. Sign up and get yours today. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Walter EJ, Hanna-Jumma S, Carraretto M, Forni L. The pathophysiological basis and consequences of fever. Crit Care. 2016 Jul 14;20(1):200. doi:10.1186/s13054-016-1375-5 Additional Reading KidsHealth, The Nemours Foundation 2018. Fever and Taking Your Child's Temperature. http://kidshealth.org/en/parents/fever.html MedlinePlus 2019. Fever. https://medlineplus.gov/ency/article/003090.htm