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There are similar but also distinctly different symptoms for COVID-19, the flu, colds, and allergies. Westend61/Getty Images
  • COVID-19, the flu, a cold, and allergies have different symptoms.
  • The main symptoms of COVID-19 are fever, tiredness, cough, and shortness of breath.
  • Allergies have more chronic symptoms and include sneezing, wheezing, and coughing.
  • The flu has symptoms similar to COVID-19, such as fever and body aches, but it doesn’t usually cause shortness of breath.

If you have a runny nose or itchy eyes, it doesn’t necessarily mean you have COVID-19.

But if you have a cough, fatigue, a fever, shortness of breath, or loss of taste or smell, there’s a much greater chance you have COVID-19.

Then again, it could also be the seasonal flu.

That’s why a good rule of thumb is, when in doubt, you may want to consider getting tested for COVID-19.

“Not all symptoms are created equally. While it might seem like you have coronavirus, you may simply be experiencing seasonal allergies or influenza,” Lindsey Elmore, PharmD, a board certified pharmacotherapy specialist and host of “The Lindsey Elmore Show,” told Healthline.

It’s worth noting, however, that the 2020-21 flu season was unusually mild, according to the Centers for Disease Control and Prevention (CDC). This is possibly due to preventive steps taken against COVID-19. Flu hospitalizations were at an all-time low last flu season, while COVID-19 cases surged, meaning that if you had flu-like symptoms, there may be a chance you actually had COVID-19.

“There are many symptoms of cold, flu, and COVID-19 that are similar, and it may be difficult to distinguish,” said Ramzi Yacoub, PharmD, chief pharmacy officer of the prescription savings service SingleCare. “They’re all caused by viruses, but different viruses cause each of these infections.”

“However, one key difference between the three is a symptom of [COVID-19] is shortness of breath,” Yacoub told Healthline. “Shortness of breath is a common symptom of COVID-19, which occurs prior to the development of pneumonia.”

“Generally, the flu or a cold does not cause shortness of breath unless it has progressed to pneumonia, in which case you’ll also want to contact your healthcare professional,” Yacoub said.

Dr. Subinoy Das, chief medical officer at Tivic Health, said the common cold rarely causes shortness of breath after fever develops.

“Influenza does mimic COVID-19 very closely, but the shortness of breath is not usually as severe as it is with COVID-19,” Das told Healthline.

With COVID-19, shortness of breath often occurs 5 to 10 days after the first sign of fever, Das said.

Health officials are expressing concerns about new variants of the coronavirus. Several variants are circulating in the United States.

The Omicron variant, first reported in late November, has raised concerns, but so far cases appear to be relatively mild.

The Delta variant still accounts for more than 90 percent of new infections.

The Delta variant was first detected in the United States in March 2021. Delta — like the others — appears to be more infectious. It causes particularly severe symptoms, although vaccinated people are still highly protected against it.

The Delta variant, which has led to more young people developing COVID-19 infections than previous variants, may also cause somewhat different symptoms than other variants.

“If you talk with pediatricians in the field, they tell you that kids are presenting with symptoms associated with the common cold and other upper respiratory infections, such as headache, runny nose, sinus congestion, and sore throat,” Dr. Inci Yildirim, a pediatric infectious disease specialist and a vaccinologist at Yale Medicine in Connecticut, told Healthline.

These symptoms are more often associated with the common cold and weren’t typically associated with earlier presentations of COVID-19.

However, Yildirim cautioned that these reports don’t necessarily mean that the Delta variant causes different symptoms, but rather may reflect COVID-19’s differing impact on younger people.

Vaccinated individuals also can get COVID-19, although their risk of infection is far lower than for unvaccinated individuals. Unvaccinated people are 5 times more likely to get COVID-19 than vaccinated people, according to the CDC, and 11 times more likely to die of the disease.

When vaccinated people do get COVID-19, they typically exhibit symptoms that are less severe than those experienced by unvaccinated people who have the infection. Research from the Zoe COVID Study, which tracks symptoms of the disease among people in the United Kingdom, found that the top symptoms for vaccinated people who get COVID are headache, runny nose, sneezing, sore throat, and persistent cough.

Vaccinated people were less likely to experience some other “traditional” symptoms of COVID-19 infection, such as shortness of breath, fever, and loss of sense of smell.

“Generally, we saw similar symptoms of COVID-19 being reported overall … by people who had and hadn’t been vaccinated,” according to a report from the Zoe COVID Study. “However, fewer symptoms were reported over a shorter period of time by people who had already had a vaccine, suggesting that they were feeling less seriously ill and getting better more quickly.”

Here’s a look at common symptoms of COVID-19, the flu, a cold, and allergies.

A runny nose, facial pain, postnasal drip, and itchy eyes are common symptoms of allergies or the common cold.

But itchy eyes and facial pain are not typical symptoms of COVID-19.

“The most common symptoms of COVID-19 are fever, tiredness, and dry cough,” according to the World Health Organization (WHO). “Some patients may have aches and pains, nasal congestion, runny nose, or sore throat.”

“In a report from China of more than 1,000 patients, nasal congestion was seen in only 1 out of every 20 patients,” Dr. Kristine S. Arthur, an internist at MemorialCare Medical Group in Laguna Woods, California, told Healthline.

However, some research suggests that COVID-19 symptoms have changed as the disease mutates and affects different populations.

Sneezing, for example, was once considered a rarer symptom of a COVID-19 infection. Now, it ranks among the most common symptoms.

COVID-19 symptoms usually appear 2 to 14 days after exposure — a window that can be wider than is typical for the flu, which usually presents symptoms within 1 to 4 days of transmission.

The CDC lists 11 primary symptoms of COVID-19:

  • fever or chills
  • cough
  • shortness of breath or difficulty breathing
  • fatigue
  • muscle or body aches
  • headache
  • new loss of taste or smell
  • sore throat
  • congestion or runny nose
  • nausea or vomiting
  • diarrhea

So far, the symptoms of the Omnicron variant appear to closely resemble those of the Delta variant.

Many of the initial people to contract this variant report muscle aches as well as fever, coughing, and shortness of breath.

However, some of them have said they did not experience a loss of taste or smell.

Some people who develop a COVID-19 infection don’t have any symptoms or feel unwell. Nevertheless, these people can still transmit the coronavirus to people around them.

COVID-19, like the flu or common cold, is an acute illness, meaning people feel fine until symptoms start showing up.

Allergies, on the other hand, “are usually chronic, presenting with symptoms off and on for weeks, months, or even years,” Dr. David M. Cutler, family medicine physician at Providence Saint John’s Health Center in Santa Monica, California, told Healthline.

“Allergies should not cause a fever or body aches,” Arthur said. “Generally, [there is] no cough unless you have a lot of nasal drainage.”

Conversely, itchy eyes and facial pain are more typical of allergies than a COVID-19 infection.

Allergies may also cause wheezing, she said, especially in people with asthma.

“Allergy symptoms tend to vary with the environment: worsening with exposure to dust, pollen, or animal dander, whereas cold symptoms tend to persist regardless of time of day, weather, locality, or other environmental factors,” Cutler said.

Also, as with COVID-19, “colds are more likely to have generalized symptoms like fever, headache, and body aches, whereas allergies usually affect only the respiratory tract,” Cutler said.

“Allergy symptoms tend to improve with antihistamine and other allergy-specific medication,” he said. “Colds are more likely to respond to decongestants, acetaminophen, fluids, and rest.”

The CDC issued guidance on the differences in symptoms between COVID-19 and seasonal allergies.

The agency said that things such as shortness of breath, coughing, fatigue, headache, and sore throat can be symptoms of either COVID-19 or allergies.

But fever, muscle aches, a loss of taste or smell, nausea, and diarrhea are associated with COVID-19 and not allergies.

Wear a mask to prevent COVID-19, flu, and allergies

To prevent COVID-19, the CDC recommends that unvaccinated people wear face masks in indoor public places. This will help slow the transmission of the coronavirus from people who don’t have symptoms or people who don’t know they have an infection.

Wearing a face mask may have the added benefit of reducing transmission of other respiratory illnesses, such as the flu, and also reduce inhalation of pollen and other allergens.

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COVID-19 is not the flu.

As one of a class of pathogens known as coronaviruses, COVID-19 is actually more closely related to the common cold than the seasonal flu.

However, despite some overlap, the typical symptoms of COVID-19 are more similar to the flu (fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, fatigue) than the common cold (runny or stuffy nose, sore throat, cough, congestion, slight body aches, mild headache, sneezing, low-grade fever, malaise).

The Delta variant, however, may have more cold-like symptoms.

“In terms of differentiating between flu and COVID-19, it can be almost impossible to distinguish,” Dr. Jake Deutsch, co-founder and clinical director of Cure Urgent Care and Specialty Infusion in New York. “That’s why people are recommended to have flu vaccinations so it can at least… minimize the risk of flu in light of everything else.”

“Fevers, body aches, coughing, sneezing could all be equally attributed to them both, so it really means that if there’s a concern for flu, there’s a concern for COVID-19,” Deutsch said.

When and where you get sick might be the best predictor of whether you have a cold, the flu, or COVID-19, Yildirim said.

People living in communities with low vaccination rates and high rates of COVID-19 “are more likely to have COVID-19,” she said, especially outside of cold and flu season.

However, she said, differentiating becomes more difficult during the winter, when all three diseases may be widespread.

If you have a mild case of COVID-19, the flu, or a cold, treatment is geared toward management of symptoms, said Cutler.

“Generally, acetaminophen is recommended for fevers,” he said. “Cough drops and cough syrups can also help keep mucous secretions thinner. If there is associated nasal congestion, antihistamines may be useful.”

Another good reason to get a flu shot is that it may help protect against severe COVID-19 symptoms like sepsis, stroke, and deep vein thrombosis, according to research from the Netherlands published in the journal PLoS One.

Also, some infectious disease experts worry that because so few people got flu infections during the 2020-21 flu season, weak natural immunity rates could cause a surge in flu infections during the 2021-22 flu season.

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Mild cases of COVID-19 are thought to last approximately 2 weeks, said Cutler.

“Fortunately, the vast majority of cases are mild,” he said.

That’s particularly true if you’re fully vaccinated against COVID-19.

Almost nobody dies from the common cold. And most seasonal allergies are more annoying than dangerous.

Influenza, however, causes between 12,000 and 52,000 deaths per year in the United States.

COVID-19 can cause more serious illness, especially among unvaccinated people, although treatments have improved in the past year. An estimated 97 percent of people hospitalized with COVID-19 disease are unvaccinated, but a study from the United Kingdom found that just 0.5 percent of COVID-19 deaths were among vaccinated individuals.

Severe symptoms of COVID-19 that require immediate medical attention include:

  • difficulty breathing
  • persistent pain or pressure in the chest
  • confusion or inability to arouse
  • bluish lips or face

Bluish lips or face indicates a shortage of oxygen in the bloodstream.

Among people who develop COVID-19 symptoms, around 15 percent have severe symptoms and need oxygen, according to the WHO.

“People ages 60 years and over, and people with underlying medical problems like high blood pressure, heart and lung problems, diabetes, obesity or cancer, are at higher risk of developing serious illness,” the WHO said.