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What does it mean if you have a fever?
How does a fever start?
Can a high temperature cause a fever?
- Mononucleosis. Symptoms. Fever. Sore throat. Fatigue. Swollen lymph nodes. Mononucleosis, or mono, is a highly contagious viral infection typically caused by the Epstein-Barr virus.
- Influenza (flu) Symptoms: Fever. Cough. Congestion. Headache. Body aches. Nausea, vomiting, diarrhea (especially in young children) The flu is an infection of the respiratory tract (e.g.,your lungs, nose, and mouth) caused by the influenza virus.
- Pneumonia. Symptoms. Fever. Cough (which may also produce mucus/phlegm) Trouble breathing or increased breathing rate. Fatigue. Chest pain. Nausea, vomiting, loss of appetite, and diarrhea (especially in younger children)
- Common cold. Symptoms. Runny nose. Cough and congestion. Low fever. Fatigue. Body aches (usually mild) A common cold is a viral infection of the respiratory tract (usually just your nose and mouth).
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Body temperatures vary slightly from person to person and at different times of day. The average temperature has traditionally been defined as 98.6 F (37 C). A temperature taken using a mouth thermometer (oral temperature) that's 100 F (37.8 C) or higher is generally considered to be a fever.
Depending on what's causing a fever, other fever signs and symptoms may include:
•Sweating
•Chills and shivering
•Headache
•Muscle aches
Infants and toddlers
A fever is a particular cause for concern in infants and toddlers. Call your baby's health care provider if your child is:
Children
There's probably no cause for alarm if your child has a fever but is responsive. This means your child makes eye contact with you and responds to your facial expressions and to your voice. Your child may also be drinking fluids and playing. Call your child's health care provider if your child:
Adults
Call your health care provider if your temperature is 103 F (39.4 C) or higher. Seek immediate medical attention if any of these signs or symptoms accompanies a fever:
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Typical body temperature is a balance of heat production and heat loss. An area in the brain called the hypothalamus (hi-poe-THAL-uh-muhs) — also known as your body's "thermostat" — monitors this balance. Even when you're healthy, your body temperature varies slightly throughout the day. It can be lower in the morning and higher in the late afternoon and evening.
When your immune system responds to disease, the hypothalamus can set your body temperature higher. This prompts complex processes that produce more heat and restrict heat loss. The shivering you might experience is one way the body produces heat. When you wrap up in a blanket because you feel chilled, you are helping your body retain heat.
Fevers below 104 F (40 C) associated with common viral infections, such as the flu, may help the immune system fight disease and are generally not harmful.
Fever or elevated body temperature might be caused by:
•A viral infection
•A bacterial infection
Children between the ages of 6 months and 5 years are at increased risk of a seizure that occurs during a fever (febrile seizure). About a third of the children who have one febrile seizure will have another one, most commonly within the next 12 months.
A febrile seizure may involve loss of consciousness, shaking of limbs on both sides of the body, eyes rolling back or body stiffness. Although alarming for parents, the vast majority of febrile seizures cause no lasting effects.
If a seizure occurs:
•Lay your child on the side or stomach on the floor or ground
•Remove any sharp objects that are near your child
•Loosen tight clothing
You may be able to prevent fevers by reducing exposure to infectious diseases. Here are some tips that can help:
•Get vaccinated as recommended for infectious diseases, such as influenza and COVID-19.
•Follow public health guidelines for wearing masks and social distancing.
•Wash your hands often and teach your children to do the same, especially before eating, after using the toilet, after spending time in a crowd or around someone who's sick, after petting animals, and during travel on public transportation.
•Show your children how to wash their hands thoroughly, covering both the front and back of each hand with soap and rinsing completely under running water.
•Carry hand sanitizer with you for times when you don't have access to soap and water.
•Mayo Clinic Minute: What to do and not do when your child has a viral fever
•Mayo Clinic Minute: Acetaminophen aids with fever, pain
•Fever treatment: Quick guide to treating a fever
•Thermometers: Understand the options
Nov 16, 2023 · What Causes Fever? A fever can be a sign of several health conditions, which may or may not need medical treatment. The most common causes are infections such as colds and stomach bugs ...
Mar 4, 2019 · So, if a virus gets into our system, it’s in the mucus membranes and it starts to show up in the bloodstream, and our immune system releases inflammatory chemicals that increase the heat in the body and increase our core temperature. Part of what happens is that it makes it very uncomfortable for the virus to live.
What are the most common causes of fever? A fever has many causes and can be a symptom of almost any illness. Common conditions that cause fever include: Bacterial infections. Viral infections such as influenza or COVID-19. Gastrointestinal (GI) infections. Urinary tract infections. Skin infections. You may also develop a fever due to:
Sep 17, 2019 · A fever begins when your immune system makes more white blood cells to fight an infection. The increase in white blood cells triggers your brain to heat your body up....
Exercise, hot weather, and common childhood immunizations can also make body temperature rise. What causes a fever? A fever is not an illness by itself. Rather it is a symptom that something is not right within the body. A fever does not tell you what is causing it, or even that a disease is present. It may be a bacterial or viral infection.
