Flu vs. Cold vs. COVID: How to Tell the Difference

With so much information circulating around and long lists of symptoms to keep track of, it can be confusing to tell different contagious respiratory viruses apart. Below, we’ve provided information on COVID vs. flu vs. cold symptoms that can help you better understand the difference between COVID-19, the flu, and the common cold.

This article is not a replacement for a medical diagnosis. Talk to your doctor if you think you may have been exposed to COVID-19 and seek emergency medical attention if you are experiencing severe symptoms such as trouble breathing, persistent chest pain or pressure, new confusion, inability to wake or stay awake, or bluish lips or face. This list does not include all possible symptoms. Please visit the Center for Disease Control for updated information regarding COVID-19.

What Is COVID-19?

COVID-19, or the Coronavirus Disease 2019, is an infectious disease caused by the coronavirus, SARS-CoV-2.^iv The primary way that coronavirus spreads is through droplets of saliva and discharge from the nose that are released into the air when a person infected with the virus coughs or sneezes.^v Coronavirus affects every person differently, but the most common symptoms are fever, dry cough, and tiredness.^vi Typically, it takes around five to six days for someone infected with the virus to show symptoms, but it can take up to 14 days for symptoms to appear.^vii

People who are older and people with underlying medical conditions like cardiovascular disease, diabetes, chronic respiratory disease, or cancer are more likely to develop serious COVID-19 symptoms, but the majority of people infected develop mild to moderate cases of the illness and can recover safely at home without special treatment or hospitalization.^viii Contact your healthcare provider if you think you may have been infected with the coronavirus. Seek immediate medical attention if you’re experiencing severe symptoms including difficulty breathing or shortness of breath, chest pressure or pain, or loss of speech or movement.

What Is the Flu?

The flu, short for “influenza,” is a contagious respiratory illness caused by the influenza virus.^ix This virus can infect the nose, throat, and lungs, causing symptoms that range from mild to severe.^x The flu typically comes on suddenly, unlike the common cold.^xi There are a range of symptoms associated with the flu but the most common include fever or chills (although not everyone with the flu will get a fever), cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue. Some people, more commonly children, will experience diarrhea or nausea.^xii

The flu is spread both in the air and from surfaces—when an infected person coughs, sneezes, or talks, they release droplets that can land in the mouths or noses of others. Someone could also become infected with the influenza virus by touching an object or surface with the virus on it and then touching their nose, mouth, or eyes.^xiii The CDC recommends getting vaccinated against the flu as the best way to avoid getting sick with the flu.^xiv

What Is the Common Cold?

Like COVID-19 and the flu, the common cold is a contagious viral respiratory illness, specifically one that infects the nose and throat.^xv Cold symptoms typically appear one to three days after someone is exposed to a virus and typically last seven to ten days.^xvi Cold symptoms vary with each individual but the most common include runny or stuffy nose, sore throat, cough, congestion, sneezing, and low-grade fever.^xvii

The common cold can be caused by numerous viruses but the most common is the rhinovirus.^xviii Like the flu, colds are spread through droplets that are released into the air when an infected person talks, sneezes, or coughs. Colds can also be spread on surfaces, hand-to-hand contact, or by sharing objects like towels or toys.^xix Possible complications of a cold include acute ear infections, asthma attacks, sinus infections, and other secondary infections like strep throat and pneumonia.^xx

COVID-19 vs. Flu: Similarities and Differences

COVID-19 and the flu are caused by different viruses but are both contagious respiratory illnesses with many similar symptoms. The virus that causes COVID-19 is a coronavirus called SARS-CoV-2, whereas the flu is caused by the influenza virus.^xxi While we are still learning about COVID-19, experts believe that COVID-19 spreads more easily, shows symptoms after a longer incubation period, remains contagious for longer, and causes more severe symptoms in some than the flu.^xxii However, research is still being done, so consult your healthcare provider or your local government to get the latest information on COVID-19.

Symptom Overlap

Many common flu symptoms are also common symptoms of COVID-19. Fever or chills, cough, shortness of breath or difficulty breathing, fatigue, sore throat, runny or stuffy nose, body aches, headache, and vomiting and diarrhea are all symptoms of both COVID-19 and the flu. Cases of both COVID-19 and the flu range from asymptomatic, meaning no symptoms are present, to severe.^xxiii One major difference in COVID vs. flu symptoms is that with COVID-19, you may experience a loss of taste or smell.^xxiv

Time Between Exposure and Infection

Flu symptoms generally take one to four days to appear after infection. COVID-19 symptoms generally appear five days after infection, but this can range from two days to 14 days after infection.^xxv

How It Spreads

Both COVID-19 and the flu are spread when an infected person talks, sneezes, or coughs, releasing droplets into the air that land in the mouths or noses or are inhaled into the lungs of others. Both COVID-19 and the flu can also be spread via surfaces, which includes shaking an infected person’s hand or touching a shared object and then touching one’s own mouth, nose, or eyes.^xxvi Someone can spread both COVID-19 and the flu to others even before they start showing symptoms.^xxvii Some ways to help mitigate the spread of COVID-19 include wearing a mask and staying at least six feet away from other people who don't live with you.

Someone with COVID-19 is contagious for longer than someone with the flu. Generally, a person with COVID-19 is contagious for 10 days after testing positive or symptoms appear whereas someone with the flu is only contagious for seven days, with days three and four days of the illness being the most contagious period.^xxviii

Who Is At Risk?

Older adults, people with underlying medical conditions, and pregnant people are all at higher risk of complications for both COVID-19 and the flu. For healthy children, the risk of complications is higher for the flu than COVID-19.^xxix

Possible complications for both COVID-19 and the flu include the following:

Respiratory failure
Pneumonia
Multiple-organ failure
Heart attack or stroke
Sepsis
Acute respiratory distress syndrome
Worsening of chronic conditions of the heart, lungs, nervous system, or diabetes
Heart, brain, or muscle tissue inflammation
Secondary bacterial infection^xxx

If you’re in a high-risk group for the flu or COVID-19, or if you experience severe symptoms for either illness, seek medical attention right away.

Conclusion

We hope this article has helped you better understand the similarities and differences between COVID vs. flu vs. cold symptoms. However, this guide is not a replacement for medical diagnosis—if you are feeling sick, make sure to talk to your doctor or trusted healthcare provider.