Table of ContentsView AllTable of ContentsFrequent SymptomsRare SymptomsComplicationsWhen to See a Healthcare ProviderFAQNext in Flu GuideHow Long Does the Flu Last?
Table of ContentsView All
View All
Table of Contents
Frequent Symptoms
Rare Symptoms
Complications
When to See a Healthcare Provider
FAQ
Next in Flu Guide
Flu symptoms can vary from person to person, but most people with influenza will experience some degree of fever, chills, headaches, body aches, congestion, coughing, and fatigue.
While the symptoms are similar to a cold or upper respiratory tract infection, the main difference is that flu symptoms hit you quickly. With the flu, you typically go from feeling fine to miserable in a matter of hours.
If you think you might have the flu,contact your healthcare providerto determine the best course of action andtreatmentfor you. Antiviral medications taken in the first 48 hours aftersymptom onsetcan reduce the severity and duration of flu symptoms.
This article discusses the symptoms of influenza. It explains the common symptoms, rare symptoms, and possible complications of the flu.
Flu symptoms come on quickly and typically last a week or two, though sometimes symptoms can linger mildly for a bit before you feel back to normal. Common symptoms include the following.
Jessica Olah / Verywell
Fever and Chills
Feveris almost always present with the flu, and it usually comes on suddenly.When you have ahigh fever, you’re also likely to experiencechillsbecause the higher your body temperature, the colder the air feels.
A fever is the body’s defense against the flu virus. Viruses thrive at a normal body temperature of 98.6 F, and while uncomfortable, running a fever helps your body fight off the flu. Whether or not to treat the fever depends on how high the temperature is and the person’s age.
A low-grade fever (98.7 F to 100.4 F) is typically not a concern for adults or most children. It may be best to let a mild fever run its course. However, if you are very uncomfortable or the fever reaches 102 F, bringing the fever down slightly is advised. Use these tactics:
When Is a Fever Is Too High?A fever of 107.6 F is considered dangerously high. It cancause brain damageand is a medical emergency.Temperatures that warrant a call to your healthcare provider include:Babies 3 months old and younger: 100.4 F (rectal)Children under 1 year: 102.2 FChildren under 2 years: 102.2 F for 24 to 48 hoursChildren older than 2: 102.2 F for 48 to 72 hours or 105 F that does not come down with treatmentAdults: 103 F or higher for 48 to 72 hours or 105 F that does not respond to treatment
When Is a Fever Is Too High?
A fever of 107.6 F is considered dangerously high. It cancause brain damageand is a medical emergency.Temperatures that warrant a call to your healthcare provider include:Babies 3 months old and younger: 100.4 F (rectal)Children under 1 year: 102.2 FChildren under 2 years: 102.2 F for 24 to 48 hoursChildren older than 2: 102.2 F for 48 to 72 hours or 105 F that does not come down with treatmentAdults: 103 F or higher for 48 to 72 hours or 105 F that does not respond to treatment
A fever of 107.6 F is considered dangerously high. It cancause brain damageand is a medical emergency.
Temperatures that warrant a call to your healthcare provider include:
What to Do for a Fever
Headache
Headaches are common with the flu and can be severe, compounding your level of discomfort. A pounding headache that comes on suddenly is often the first sign of influenza.In some people, the flu triggers migraines with sensitivity to light, sound, and smell.
Several factors play a role in headaches with the flu. First, the immune system releases increasing inflammatory cytokines to fight the infection. Cytokines are known to trigger headaches and migraines and are the primary suspect behind flu headaches.
Another possible cause of headaches with flu is inflammation of the mucous membranes lining the nasal and sinus cavities. Part of the immune reaction to the influenza virus, this inflammation causes pressure around the eyes and face, which can lead to a headache.
An over-the-counter (OTC) pain reliever like acetaminophen or ibuprofen may help ease the pain.
What Causes Diarrhea and Chills? 6 Possible Conditions
Exhaustion
One of the most significant symptoms that people describe when they get the flu is pure exhaustion.This is generally an overall feeling of being completely worn out.
You probably will be unable to perform daily activities, and fatigue is often so severe that it is hard to just get out of bed. This exhaustion is much more pronounced than the tiredness you may feel from a cold.
1:51Click Play to Learn About the Symptoms of the Flu
1:51
Click Play to Learn About the Symptoms of the Flu
Aches and Pains
Feeling achy is how many people with the flu describe their state. Your muscles are usually very sore, and moving around too much causes discomfort. Body aches andpainsare more common with the flu than with many other illnesses.
How to Relieve Body Aches When You’re Sick
Coughing
Coughing may be productive (producing mucus) or non-productive. With the flu, people most often have adry cough.
If you develop aproductive coughwith fever, contact your healthcare provider. This is especially true if you have had a dry cough, start to feel better, then have a wet or productive cough with a fever.This is often how a secondary infection, like pneumonia, develops.
Congestion
Severe congestionis more common when you have a cold, but many people will experience some congestion with the flu as well. It is typically mild.
Vomiting and diarrhea are not common flu symptoms for most people, but some do experience them. Children are more likely to have vomiting and diarrhea with influenza than adults.
If vomiting and diarrhea are your primary and most significant symptoms, you probably have a stomach bug instead (sometimes referred to as thestomach flu, though it is not influenza).
Seasonal Flu vs. Stomach Flu
For most people, flu symptoms resolve in one to two weeks. Complications are typically mild, such as sinus or ear infections.
The flu can, however, be serious and life-threatening. In fact, there are 12,000 to 61,000 deaths from influenza in the United States each year.
Serious complications of the flu can include:
High-Risk GroupsThose at higher risk of complications from the flu include:Adults ages 65 and olderPeople who arepregnantChildren under the age of 5People with chronic medical conditions such as asthma, diabetes, and heart diseaseThose who are immunocompromised
High-Risk Groups
Those at higher risk of complications from the flu include:Adults ages 65 and olderPeople who arepregnantChildren under the age of 5People with chronic medical conditions such as asthma, diabetes, and heart diseaseThose who are immunocompromised
Those at higher risk of complications from the flu include:
If, based on the symptoms, you believe you may have the flu, call your healthcare provider right away. Antiviral medications such asTamiflucan lessen the severity and duration of the flu if started within the first 48 hours of symptom onset.
Your healthcare provider may want you to come in to confirm the influenza virus with a rapid in-office test or may prescribe an antiviral solely based on your symptoms and flu activity in your area.
You should also contact your healthcare provider if symptoms continue to worsen after a week, or if you develop a fever or productive cough after you have started to feel better. This could indicate a secondary infection, such as bronchitis or pneumonia.
Other symptoms that require a call to your healthcare provider include severe muscle pain, weakness, or unsteadiness, and any worsening of chronic medical conditions.
When to Call 911
The flu can quickly take a turn for the worse and may require emergency care. If you experience any of the following symptoms, seek immediate medical attention, as these may be a sign of serious or life-threatening complications:
In children, seek immediate medical attention for these symptoms:
Frequently Asked Questions
Symptoms can begin between one and four days after you’ve been exposed to the virus. Even though you’re most contagious after your illness begins, it is possible to give the flu to someone else before you realize you’re sick.
At-home remediesfor mild symptoms include getting lots of rest, drinking fluids to prevent dehydration, and taking over-the-counter medications like Advil (ibuprofen) or Tylenol (acetaminophen) for fever and discomfort. Do not give aspirin to children or teenagers, as it can lead to a dangerous condition calledReye’s syndrome.
11 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.Flu symptoms & complications.U.S. National Library of Medicine: MedlinePlus.Fever.National Headache Foundation.What your flu headache is telling you.Musubire AK, Cheema S, Ray JC, Hutton EJ, Matharu M.Cytokines in primary headache disorders: a systematic review and meta-analysis.J Headache Pain. 2023;24(1):36. doi:10.1186/s10194-023-01572-7Arca KN, Halker Singh RB.Dehydration and headache.Curr Pain Headache Rep. 2021;25(8):56. doi:10.1007/s11916-021-00966-zU.S. National Library of Medicine: MedlinePlus.Flu.American Lung Association.What are the symptoms of pneumonia?Centers for Disease Control and Prevention.Disease burden of influenza.Centers for Disease Control and Prevention.How flu spreads.U.S. Food and Drug Administration.Highlights of Prescribing Information: Tamiflu (oseltamivir phosphate).U.S. Food and Drug Administration.Tamiflu: Consumer questions and answers.
11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.Flu symptoms & complications.U.S. National Library of Medicine: MedlinePlus.Fever.National Headache Foundation.What your flu headache is telling you.Musubire AK, Cheema S, Ray JC, Hutton EJ, Matharu M.Cytokines in primary headache disorders: a systematic review and meta-analysis.J Headache Pain. 2023;24(1):36. doi:10.1186/s10194-023-01572-7Arca KN, Halker Singh RB.Dehydration and headache.Curr Pain Headache Rep. 2021;25(8):56. doi:10.1007/s11916-021-00966-zU.S. National Library of Medicine: MedlinePlus.Flu.American Lung Association.What are the symptoms of pneumonia?Centers for Disease Control and Prevention.Disease burden of influenza.Centers for Disease Control and Prevention.How flu spreads.U.S. Food and Drug Administration.Highlights of Prescribing Information: Tamiflu (oseltamivir phosphate).U.S. Food and Drug Administration.Tamiflu: Consumer questions and answers.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Centers for Disease Control and Prevention.Flu symptoms & complications.U.S. National Library of Medicine: MedlinePlus.Fever.National Headache Foundation.What your flu headache is telling you.Musubire AK, Cheema S, Ray JC, Hutton EJ, Matharu M.Cytokines in primary headache disorders: a systematic review and meta-analysis.J Headache Pain. 2023;24(1):36. doi:10.1186/s10194-023-01572-7Arca KN, Halker Singh RB.Dehydration and headache.Curr Pain Headache Rep. 2021;25(8):56. doi:10.1007/s11916-021-00966-zU.S. National Library of Medicine: MedlinePlus.Flu.American Lung Association.What are the symptoms of pneumonia?Centers for Disease Control and Prevention.Disease burden of influenza.Centers for Disease Control and Prevention.How flu spreads.U.S. Food and Drug Administration.Highlights of Prescribing Information: Tamiflu (oseltamivir phosphate).U.S. Food and Drug Administration.Tamiflu: Consumer questions and answers.
Centers for Disease Control and Prevention.Flu symptoms & complications.
U.S. National Library of Medicine: MedlinePlus.Fever.
National Headache Foundation.What your flu headache is telling you.
Musubire AK, Cheema S, Ray JC, Hutton EJ, Matharu M.Cytokines in primary headache disorders: a systematic review and meta-analysis.J Headache Pain. 2023;24(1):36. doi:10.1186/s10194-023-01572-7
Arca KN, Halker Singh RB.Dehydration and headache.Curr Pain Headache Rep. 2021;25(8):56. doi:10.1007/s11916-021-00966-z
U.S. National Library of Medicine: MedlinePlus.Flu.
American Lung Association.What are the symptoms of pneumonia?
Centers for Disease Control and Prevention.Disease burden of influenza.
Centers for Disease Control and Prevention.How flu spreads.
U.S. Food and Drug Administration.Highlights of Prescribing Information: Tamiflu (oseltamivir phosphate).
U.S. Food and Drug Administration.Tamiflu: Consumer questions and answers.
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