If your throat starts itching or you feel fatigued, how are you supposed to know what virus you have? It’s an important question, as treatments for the flu, COVID-19 and the common cold are different, and passing COVID-19 onto a family member can have more severe consequences than passing along a milder coronavirus that causes the common cold, for example.
So far this fall, all signs point to a troubling flu season, with the total number of people hospitalized by the week ending on Oct. 29 higher than every year prior at this point in the season as far back as the 2010-2011 flu season, according to a report from the US Centers for Disease Control and Prevention. COVID-19 also remains a threat in the US, with roughly 350 deaths in the US per day.
Because of COVID-19’s potential to be deadly for some people, you should isolate while you feel sick or until you get your results from a COVID-19 test, which are readily available these days at pharmacies and online. Influenza, which causes the flu, can also be very severe or even deadly for certain folks, including older adults and very young children. To be on the safe side, you should always stay home when you feel unwell if at all possible — especially if you have a fever, which is a signal your body is in the active throes of fighting some sort of infection.
Whether or not you’re currently feeling sick, it’s a good time to understand the differences between the three illnesses and what specific symptoms could mean. We also spoke with medical experts to learn the best ways of protecting yourself and your loved ones from diseases this season.
Whether or not you’re currently feeling sick, it’s a good time to understand the differences between the three illnesses and what specific symptoms could mean. We also spoke with medical experts to learn the best ways of protecting yourself and your loved ones from diseases this season.
Symptoms of COVID-19, the flu, the common cold and RSV commonly overlap in adults
Though COVID-19, influenza and colds are all caused by different viruses, many of their symptoms overlap. It is also possible to be infected with more than one virus at a time. As some people’s immune systems become better at fighting COVID-19 through vaccines, booster doses, prior infections and the availability of antivirals like Paxlovid, illnesses may become milder and some may be more likely to brush a COVID-19 infection off as a cold.
Although the loss of smell and taste was the defining unique symptom of COVID-19 earlier in the pandemic, it’s less common with the currently dominant omicron variant. The only way to diagnose your illness for certain is to test for both flu and COVID-19.
In very young children, respiratory syncytial virus can cause symptoms in addition to respiratory problems or flu or cold-like symptoms. Fussiness, losing interest in playing, or seeming more tired than normal may all be symptoms of RSV in babies and toddlers. You can read more about RSV in children here.
What are common symptoms of the flu and COVID-19?
Many respiratory illnesses start with similar symptoms. It may not be easy to immediately figure out whether you’re sick with the flu or COVID-19, but here are some symptoms the two share.
- Fever
- Cough
- Difficulty breathing or shortness of breath
- Sore throat
- Runny nose or congestion
- Headache
- Body aches
- Fatigue
If you feel sick with any of these symptoms, it’s best to isolate yourself right away. You can spread the flu and COVID-19 one day after being infected. Keep in mind that these symptoms may be signs of other viruses, such as the ones that cause the common cold, or RSV. Call your primary care provider for questions and the best next steps.
Remember that COVID-19 isn’t only a respiratory illness — it can also affect a number of other systems in the body, including the heart, brain and nerves. Scientists and medical experts are still defining the range of possible damage from COVID-19.
What are the most common symptoms of COVID-19 right now?
Generally speaking, it’s hard to pin down the “most common” symptom of COVID-19, because the virus that causes it changes slightly with each mutation, and people now have varying levels of immunity depending on their vaccination history, previous infections and individual health. But Zoe, a health science company, has been collecting the most common symptoms in people with COVID-19 through the company’s COVID Study app. As of Oct. 20, Zoe reports the following top five symptoms in people who’ve had two vaccines:
- Sore throat
- Runny nose
- Blocked nose
- Persistent cough
- Headache
While these all are flu-like symptoms, if you experience any of these symptoms in the coming weeks, it may be a strong indicator that you have COVID-19.
What are the differences between the flu and COVID-19?
The two most notable differences between COVID-19 and the flu are the time it takes for symptoms to show up, and the loss of taste and smell. It generally takes a little longer for COVID-19 symptoms to present after exposure — two to five days (but up to 14) for COVID-19 versus one to four days for the flu, according to the CDC.
The loss of taste and smell is a specific symptom to COVID-19 that is generally not associated with the flu. However, that symptom was more prevalent with early COVID-19 variants and doesn’t appear to be as common with the different versions of omicron.
Another difference between the two viruses is that you could be contagious for longer with COVID-19 than you would be with the flu. Per the CDC, older children and adults with the flu are most contagious through their third or fourth day of symptoms, while people with COVID-19 are contagious, on average, for eight days after their symptoms start.
Symptoms of the flu and COVID-19 can both lead to hospitalization and death. Dr. David Hamer, a Boston University School of Public Health professor and physician at Boston Medical Center, agreed that the symptoms aren’t easy to differentiate right away. “Clinically, it’s going to be harder for an individual to differentiate. COVID is a little more likely to progress to a severe disease, but certainly, influenza can kill,” Hamer said.
An at-home COVID-19 test can help determine your illness.
Stephen Shankland/CNET
How do I know if I have a cold or something worse?
The symptoms of the common cold are also similar to COVID-19 and the flu, but there are some differences. Fevers aren’t as common with a cold, for example, and COVID-19 and the flu are more likely to knock you out of commission, fatigue-wise, for longer than a cold would. You’re also less likely to feel “achy” when you have a cold, as another example from the Mayo Clinic.
Like COVID-19, you may notice symptoms such as cough, sore throat and a runny nose. But common colds usually also come with sneezing, watery eyes and post-nasal drip.
Usually, common colds resolve on their own and don’t lead to further health complications and often can be treated with over-the-counter medication.
“If there’s fever, body aches or chills, that would make me more concerned about other respiratory illnesses — like the flu or COVID,” said Dr. Daniel Solomon, an infectious disease doctor at Brigham and Women’s Hospital. Since the COVID-19 vaccine helps prevent severe symptoms, more common signs of a cold can still be COVID, he added.
Because of this, Solomon has guided his patients and family members to pay close attention to their usual allergy symptoms and get a diagnostic test if they notice anything less common.
What is the best way to protect yourself and others from COVID-19 and the flu?
The best protection against both COVID-19 and the flu is vaccination. Medical experts advise that you can safely receive both the flu and COVID-19 shots simultaneously. That includes the new updated boosters. You may also reach out to your doctor as soon as you develop any respiratory symptoms, so you can get the appropriate antiviral treatments or other care, if necessary. This is especially important if you’re an older adult or have an underlying medical condition (or have a very young child), as you might be at higher risk of severe disease.
Beyond getting vaccinated, wearing a mask in public, washing your hands before eating or touching your face, avoiding indoor crowds and people who have symptoms are tried and true ways to cut down on your risk of getting a respiratory virus.
What are other common illnesses similar to COVID-19 and the flu?
If you have a cough, sore throat or other respiratory illness symptoms, it may not be COVID-19, the flu or a cold. There are other common illnesses with similar symptoms.
- Sinus infections
- Strep throat
- Bronchiolitis
- Asthma
If you tested negative for COVID-19 and the flu, it’s best to consult with your primary care provider. Some doctors will conduct a respiratory pathogens panel to determine what virus or bacteria is causing you to feel sick.
CNET contributor Mercey Livingston contributed to this article.
The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.