Cold Versus Flu, How To Know The Differences
Flu and the common cold are both respiratory illnesses but they are caused by different viruses. Because these two types of illnesses have similar symptoms, it can be difficult to tell the difference between them based on symptoms alone.
In general, flu is worse than the common cold, and symptoms are more intense. Colds are usually milder than flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems, such as pneumonia, bacterial infections, or hospitalizations. Flu can have very serious associated complications.
- How can you tell the difference between a cold and the flu?
Cold or Flu?
Because colds and flu share many symptoms, it can be difficult (or even impossible) to tell the difference between them based on symptoms alone. Special tests that usually must be done within the first few days of illness can tell if a person has the flu.
- What are the symptoms of the flu versus the symptoms of a cold?
The symptoms of flu can include fever or feeling feverish/chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and fatigue (tiredness).
Cold symptoms are usually milder than the symptoms of flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems.
Similarities and Differences between Flu and COVID-19How Long Symptoms Appear After Exposure and Infection How Long Someone Can Spread the Virus
How it Spreads
People at High-Risk for Severe Illness
What is the difference between Influenza (Flu) and COVID-19?
Influenza (flu) and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by infection with a coronavirus first identified in 2019, and flu is caused by infection with influenza viruses.
COVID-19 seems to spread more easily than flu. However, as more people become fully vaccinated against COVID-19, the spread of the virus that causes COVID-19 should slow down.
Compared to flu, COVID-19 can cause more serious illnesses in some people. COVID-19 can also take longer before people show symptoms and people can be contagious for longer.
Because some of the symptoms of flu, COVID-19, and other respiratory illnesses are similar, the difference between them cannot be made based on symptoms alone. Testing is needed to tell what the illness is and to confirm a diagnosis.
People can be infected with both flu and the virus that causes COVID-19 at the same time and have symptoms of both influenza and COVID-19.
While more is learned every day about COVID-19 and the virus that causes it, there are still things, such as post-COVID conditions, that are unknown. This page compares COVID-19 and flu, given the best available information to date.
More about how to protect yourself and others from COVID-19.
Both COVID-19 and flu can have varying degrees of signs and symptoms, ranging from no symptoms (asymptomatic) to severe symptoms. Common symptoms that COVID-19 and flu share include:
Fever or feeling feverish/having chills
Shortness of breath or difficulty breathing
Runny or stuffy nose
Muscle pain or body aches
Vomiting and diarrhea
Change in or loss of taste or smell, although this is more frequent with COVID-19.
- Flu Symptoms
- COVID-19 Symptoms
- How Long Symptoms Appear After Exposure and Infection
For both COVID-19 and flu, 1 or more days can pass between when a person becomes infected and when he or she starts to experience illness symptoms.
If a person has COVID-19, it could take them longer to experience symptoms than if they had flu.
Typically, a person experiences symptoms anywhere from 1 to 4 days after infection.
Typically, a person experiences symptoms about 5 days after being infected, but symptoms can appear 2 to 14 days after infection.
How Long Someone Can Spread the Virus
For both COVID-19 and flu, it’s possible to spread the virus for at least 1 day before experiencing any symptoms.
If a person has COVID-19, they could be contagious for a longer time than if they had flu.
Most people with flu are contagious for about 1 day before they show symptoms.
Older children and adults with flu appear to be most contagious during the initial 3-4 days of their illness but many people remain contagious for about 7 days.
Infants and people with weakened immune systems can be contagious for even longer.
How Flu Spreads
How long someone can spread the virus that causes COVID-19 is still under investigation.
It’s possible for people to spread the virus for about 2 days before experiencing signs or symptoms (or possibly earlier) and remain contagious for at least 10 days after signs or symptoms first appeared. If someone is asymptomatic or their symptoms go away, it’s possible to remain contagious for at least 10 days after testing positive for COVID-19. People who are hospitalized with severe disease and people with weakened immune systems can be contagious for 20 days or longer.
How COVID-19 Spreads
Both COVID-19 and flu can spread from person-to-person between people who are in close contact with one another (within about 6 feet). Both are spread mainly by large and small particles containing virus that are expelled when people with the illness (COVID-19 or flu) cough, sneeze, or talk. These particles can land in the mouths or noses of people who are nearby and possibly be inhaled into the lungs. In some circumstances, such as indoor settings with poor ventilation, small particles might be spread further than 6 feet and cause infections.
Although most spread is by inhalation, it may be possible that a person can get infected by touching (for example, shaking hands with someone who has the virus on their hands) or by touching a surface or object that has virus on it, and then touching their own mouth, nose, or eyes.
Both flu viruses and the virus that causes COVID-19 can be spread to others by people before they begin showing symptoms; by people with very mild symptoms; and by people who never experience symptoms (asymptomatic people).
While the virus that causes COVID-19 and flu viruses are thought to spread in similar ways, the virus that causes COVID-19 is generally more contagious than flu viruses. Also, COVID-19 has been observed to have more super-spreading events than flu. This means the virus that causes COVID-19 can quickly and easily spread to a lot of people and result in continual spreading among people as time progresses.
How Flu Spreads How COVID-19 Spreads
People at High-Risk for Severe Illness
Both COVID-19 and flu illness can result in severe illness and complications.
Those at highest risk include:
People with certain underlying medical conditions (including infants and children)
Overall, COVID-19 seems to cause more serious illnesses in some people.
For young children, especially children younger than 5 years old, the risk of serious complications is higher for flu compared with COVID-19. However, serious COVID-19 illness resulting in hospitalization and death can occur even in healthy young children.
Compared to young children, teens and adolescents with COVID-19 are more likely to have Multi-system Inflammatory Syndrome in Children (MIS-C), a rare but severe complication of COVID-19. However, for adolescents, the risk of serious COVID-19 illness is less than in children younger than 5.
People at Increased Risk of COVID-19 Severe Illness
Both COVID-19 and flu can result in complications, including:
Acute respiratory distress syndrome (fluid in the lungs)
Sepsis (a life-threatening illness caused by the body’s extreme response to an infection)
Cardiac injury (for example, heart attacks and stroke)
Multiple-organ failure (respiratory failure, kidney failure, shock)
Worsening of chronic medical conditions (involving the lungs, heart, or nervous system or diabetes)
Inflammation of the heart, brain, or muscle tissues
Secondary infections (bacterial or fungal infections that can occur in people who have already been infected with flu or COVID-19)
Most people who get flu will recover on their own in a few days to two weeks, but some people will experience severe complications, requiring hospitalization. Some of these complications are listed above. Secondary bacterial infections are more common with influenza than with COVID-19.
Diarrhea is more common in young children with flu than in adults with flu.
COVID-19 Additional complications associated with COVID-19 can include:
Blood clots in the veins and arteries of the lungs, heart, legs or brain
Multisystem Inflammatory Syndrome in Children (MIS-C) and in Adults (MIS-A)
Long COVID is a range of symptoms that can last weeks or months after first being infected with the virus that causes COVID-19 or can appear weeks after infection. Long COVID can happen to anyone who has had COVID-19, even if their illness was mild, or if they had no symptoms.
People at higher risk of complications or who have been hospitalized for COVID-19 or flu should receive supportive medical care to help relieve symptoms and complications.
Prescription influenza antiviral drugs are FDA-approved to treat flu.
People who are hospitalized with flu or who are at increased risk of complications and have flu symptoms are recommended to be treated with antiviral drugs as soon as possible after illness onset.
The National Institutes of Health (NIH) has developed guidance on treatment of COVID-19 which is regularly updated as new evidence on treatment options emerges.
The Food and Drug Administration (FDA) has approved one drug, remdesivir (Veklury®), to treat COVID-19. FDA has issued emergency use authorizations (EUAs) to allow healthcare providers to use investigational products that are not yet approved, or that are approved for other uses, to treat patients with COVID-19 if certain legal requirements are met.
What to Do If You Are Sick with COVID-19
What to Do If You Are Sick
Updated Mar. 17, 2021
If you have a fever, cough or other symptoms, you might have COVID-19. Most people have mild illness and are able to recover at home.
If you are sick:
Keep track of your symptoms.
If you have an emergency warning sign (including trouble breathing), call 911.
Steps to help prevent the spread of COVID-19 if you are sick
If you are sick with COVID-19 or think you might have COVID-19, follow the steps below to care for yourself and to help protect other people in your home and community.
Stay home except to get medical care
Stay home. Most people with COVID-19 have mild illness and can recover at home without medical care. Do not leave your home, except to get medical care. Do not visit public areas.
Take care of yourself. Get rest and stay hydrated. Take over-the-counter medicines, such as acetaminophen, to help you feel better.
Stay in touch with your doctor. Call before you get medical care. Be sure to get care if you have trouble breathing, or have any other emergency warning signs, or if you think it is an emergency.
Avoid public transportation, ride-sharing, or taxis.
Separate yourself from other people
As much as possible, stay in a specific room and away from other people and pets in your home. If possible, you should use a separate bathroom. If you need to be around other people or animals in or outside of the home, wear a mask.
Tell your close contacts that they may have been exposed to COVID-19. An infected person can spread COVID-19 starting 48 hours (or 2 days) before the person has any symptoms or tests positive. By letting your close contacts know they may have been exposed to COVID-19, you are helping to protect everyone.
Additional guidance is available for those living in close quarters and shared housing.
See COVID-19 and Animals if you have questions about pets.
If you are diagnosed with COVID-19, someone from the health department may call you. Answer the call to slow the spread.
Monitor your symptoms
Symptoms of COVID-19 include fever, cough, or other symptoms.
Follow care instructions from your healthcare provider and local health department. Your local health authorities may give instructions on checking your symptoms and reporting information.
When to seek emergency medical attention
Look for emergency warning signs* for COVID-19. If someone is showing any of these signs, seek emergency medical care immediately:
Persistent pain or pressure in the chest
Inability to wake or stay awake
Pale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone
*This list is not all possible symptoms. Please call your medical provider for any other symptoms that are severe or concerning to you.
Call 911 or call ahead to your local emergency facility: Notify the operator that you are seeking care for someone who has or may have COVID-19.
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Call ahead before visiting your doctor
Call ahead. Many medical visits for routine care are being postponed or done by phone or telemedicine.
If you have a medical appointment that cannot be postponed, call your doctor’s office, and tell them you have or may have COVID-19. This will help the office protect themselves and other patients.
If you have symptoms of COVID-19, get tested. While waiting for test results pdf icon[224 KB, 2 pages], you stay away from others, including staying apart from those living in your household.
You can visit your state, tribal, localexternal icon, and territorial health department’s website to look for the latest local information on testing sites.
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If you are sick, wear a mask over your nose and mouth
You should wear a mask over your nose and mouth if you must be around other people or animals, including pets (even at home).
You don’t need to wear the mask if you are alone. If you can’t put on a mask (because of trouble breathing, for example), cover your coughs and sneezes in some other way. Try to stay at least 6 feet away from other people. This will help protect the people around you.
Masks should not be placed on young children under age 2 years, anyone who has trouble breathing, or anyone who is not able to remove the mask without help.
Note: During the COVID-19 pandemic, medical grade facemasks are reserved for healthcare workers and some first responders.
Cover your coughs and sneezes
Cover your mouth and nose with a tissue when you cough or sneeze.
Throw away used tissues in a lined trash can.
Immediately wash your hands with soap and water for at least 20 seconds. If soap and water are not available, clean your hands with an alcohol-based hand sanitizer that contains at least 60% alcohol.
Clean your hands often
Wash your hands often with soap and water for at least 20 seconds. This is especially important after blowing your nose, coughing, or sneezing; going to the bathroom; and before eating or preparing food.
Use hand sanitizer if soap and water are not available. Use an alcohol-based hand sanitizer with at least 60% alcohol, covering all surfaces of your hands and rubbing them together until they feel dry.
Soap and water are the best option, especially if hands are visibly dirty.
Avoid touching your eyes, nose, and mouth with unwashed hands.
Avoid sharing personal household items
Do not share dishes, drinking glasses, cups, eating utensils, towels, or bedding with other people in your home.
Wash these items thoroughly after using them with soap and water or put in the dishwasher.
Clean all “high-touch” surfaces everyday
Clean and disinfect high-touch surfaces in your “sick room” and bathroom; wear disposable gloves. Let someone else clean and disinfect surfaces in common areas, but you should clean your bedroom and bathroom, if possible.
If a caregiver or other person needs to clean and disinfect a sick person’s bedroom or bathroom, they should do so on an as-needed basis. The caregiver/other person should wear a mask and disposable gloves prior to cleaning. They should wait as long as possible after the person who is sick has used the bathroom before coming in to clean and use the bathroom.
High-touch surfaces include phones, remote controls, counters, tabletops, doorknobs, bathroom fixtures, toilets, keyboards, tablets, and bedside tables.
Clean and disinfect areas that may have blood, stool, or body fluids on them.
Use household cleaners and disinfectants. Clean the area or item with soap and water or another detergent if it is dirty. Then, use a household disinfectant.
Be sure to follow the instructions on the label to ensure safe and effective use of the product. Many products recommend keeping the surface wet for several minutes to ensure germs are killed. Many also recommend precautions such as wearing gloves and making sure you have good ventilation during use of the product.
Use a product from EPA’s List N: Disinfectants for Coronavirus (COVID-19)
Complete Disinfection Guidance
When you can be around others after being sick with COVID-19
Deciding when you can be around others is different for different situations. Find out when you can safely end home isolation.
For any additional questions about your care, contact your healthcare provider or state or local health department.
Also see these articles
Additional Considerations for Workers Who Reside in Communal Living Arrangements https://www.osha.gov/coronavirus/control-prevention/workers-in-shared-housing
Protect Yourself Living with Other People https://www.cdc.gov/coronavirus/2019-ncov/easy-to-read/living-in-close-quarters.html
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