How do I know if it's Covid-19, a Cold, or the Flu?

Published on Nov 27, 2023 | 1:23 PM

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In the United States, the colder months are often looked upon fondly, thanks to the holiday season, potential snow days, and the beautiful displays of community shown across the country. However, for those in the medical field, the holiday season and the months thereafter make up some of the busiest days of the year, thanks to the many diseases and infections that run rampant in the colder months. 

With many of the seasonal conditions such as diseases like the common cold, influenza, and Covid sharing many of their symptoms, the doctors at CallonDoc get many patients who are unsure what they have. Here, we will go over a bit of information about all three and how to differentiate between them so you can get more out of any doctor’s visit!

Examining Covid-19, a cold, and the flu symptoms

When looking at the symptoms alone, it's no small wonder why people get Covid-19, colds, and the flu confused. Each shares similar symptoms, with some cases mirroring each other, but having different causes. With references to CallonDoc’s Guides to the flu and Covid, here are the most common symptoms of each:

Common Cold:

  • Runny or Stuffy Nose: A common cold often begins with nasal congestion or a runny nose, with mucus production contributing to the feeling of stuffiness.
  • Sneezing: Frequent sneezing is typical as the body attempts to expel the virus from the nasal passages.
  • Sore Throat: Irritation or discomfort in the throat is common due to viral inflammation.
  • Cough: A mild cough, often producing phlegm, may develop as the virus affects the respiratory tract.
  • Fatigue: Feeling tired is common, but the fatigue is generally mild compared to more severe illnesses.
  • Mild Headache: Headaches are typically mild and may result from nasal congestion or other cold symptoms.
  • Watery Eyes: Excess tearing can occur as a response to nasal congestion and irritation.
  • Mild Body Aches: Generalized body discomfort and mild muscle aches can accompany a cold, but relatively minor compared to more severe illnesses

Flu (Influenza):

  • Fever: The flu often presents with a sudden onset of high fever, signaling the body's immune response.
  • Cough: A persistent, dry cough is common and can be severe, contributing to overall respiratory distress.
  • Sore Throat: Throat pain may result from inflammation caused by the influenza virus.
  • Runny or Stuffy Nose: Nasal congestion or a runny nose can occur, though respiratory symptoms are more severe than in a cold.
  • Body Aches (Myalgia): Severe muscle aches and pains are typical and can be debilitating.
  • Headache: Intense headaches are common and contribute to the overall feeling of illness.
  • Fatigue: Profound fatigue and weakness are characteristic and can persist for an extended period.
  • Chills: Shivering and chills often accompany the onset of fever.


  • Fever: Elevated body temperature is a common sign, often exceeding 100.4°F (38°C), indicating a potential viral infection.
  • Dry Cough: A persistent, dry cough is a recognizable symptom, distinct from a cough associated with a cold due to its lack of phlegm.
  • Shortness of Breath or Difficulty Breathing: Respiratory distress, particularly difficulty breathing, may be indicative of a more severe case.
  • Loss of Taste or Smell: Sudden loss or alteration of taste and smell can be a unique and early indicator of COVID-19.
  • Fatigue: Feeling unusually tired or exhausted is a common manifestation, often persisting throughout the illness.
  • Muscle or Body Aches: Generalized body pain or muscle soreness can contribute to overall discomfort.
  • Headache: Headaches are reported and can range from mild to severe, resembling flu-like symptoms.
  • Sore Throat: Throat discomfort may occur, although it is generally less prominent than in some other respiratory illnesses.
  • Congestion or Runny Nose: Nasal symptoms can vary, with some experiencing congestion or a runny nose.
  • Nausea or Vomiting: Gastrointestinal symptoms like nausea and vomiting have been reported, though less frequently than respiratory symptoms.
  • Diarrhea: Some individuals with COVID-19 may experience diarrhea, particularly in conjunction with other symptoms.
  • Chills: Shivering and chills can accompany the fever associated with COVID-19.
  • Persistent Chest Pain or Pressure: Severe cases may involve persistent chest pain or pressure, requiring immediate medical attention.
  • Confusion (particularly in older adults): Cognitive symptoms, including confusion, have been reported, particularly in older adults.

How do you know if you have a cold or the flu?

Distinguishing between a cold and the flu can be challenging due to their shared symptoms. Generally, cold symptoms develop gradually, with a rare occurrence of fever in adults. Coughing is usually mild, sore throat is common, and nasal symptoms are prevalent. The duration of a cold is typically around one week.

Symptoms Shared Between Influenza and the Common Cold

  • Cough: Both the flu and the common cold can cause a cough. The cough may be dry or productive, and it is a common respiratory symptom in both illnesses.
  • Sore Throat: A sore throat is a symptom that can be present in both the flu and the common cold. It may range from mild to moderate and is often one of the early symptoms.
  • Fatigue: Feeling tired or fatigued is a shared symptom between the flu and the common cold. Both illnesses can cause a general sense of tiredness and malaise.
  • Headache: Headaches are common symptoms in both influenza and the common cold. They can result from the body's immune response to the viral infection.
  • Body Aches: Muscle or body aches, also known as myalgia, are symptoms commonly seen in both the flu and the common cold. These aches are often a manifestation of the body's inflammatory response.
  • Fever: Fever is a prominent symptom in both influenza and the common cold. 
  • Chills: Chills can occur in both influenza and the common cold. They are often associated with fever and are part of the body's effort to increase its temperature.

On the other hand, flu symptoms emerge suddenly and often include a high fever, severe cough, body aches, fatigue, headache, and chills. While sore throat is less common with the flu, muscle and body aches are more pronounced. Flu symptoms can last over a week, and fatigue may persist for several weeks.

Symptoms Shared Between Covid and the Common Cold: 

  • Cough: Both COVID-19 and the common cold can cause a cough. 
  • Sore Throat: A sore throat is a common symptom in both cases, though it may be more prevalent in the common cold.
  • Fatigue: Feeling tired or fatigued can be a symptom of both COVID-19 and the common cold.
  • Headache: Headaches are a common symptom in both illnesses.
  • Body Aches: Muscle or body aches can occur with both COVID-19 and the common cold.
  • Fever: Fever can occur in both COVID-19 and the common cold.

In addition to symptoms, the onset and progression of the illness can provide clues. COVID-19 symptoms often appear suddenly and may be more severe and persistent than those of a common cold. Whereas there is no test for the common cold, tests for Covid-19 are prevalent and can provide you with a conclusive answer to whether you have the disease or not. 

Differentiating between COVID-19 and a common cold involves considering various symptoms. While both may include coughing, fatigue, and a sore throat, COVID-19 tends to present with distinct features such as a sudden loss of taste or smell, persistent cough, and difficulty breathing. Fever is also more common in COVID-19 than in the typical adult cold.

Notable Differences between the Common Cold and Influenza

  • Shortness of Breath and Difficulty Breathing: Shortness of breath and difficulty breathing are more commonly associated with COVID-19 due to the SARS-CoV-2 virus primarily infecting cells in the lower respiratory tract, leading to inflammation and potentially severe respiratory complications. Shortness of breath can happen with influenza, but typcially is asscociated with a rarer and more severe case. 
  • Loss of Taste or Smell: An abrupt loss of taste or smell is strongly associated with COVID-19, as the SARS-CoV-2 virus can directly affect the olfactory bulb. Influenza doesn’t typically affect the olfactory bulb and a patient’s senses, aside from occassionally dulling a person’s sense of taste and smell through heavy congestion.
  • Fever: Compared to Covid, flu cases more prominently feature fever that appears as immediately alongside other symptoms. While it can be considered high, it tends to die down after a few days to just over a week. The fever with Covid gradually appears, more often staying higher for longer.
  • Gastrointestinal Symptoms: Gastrointestinal symptoms such as nausea, vomiting, and diarrhea can occur with COVID-19 due to the virus's ability to infect cells in the gastrointestinal tract. While less common with the flu, vomiting and diarrhea can still happen at a mild level. 
  • Severity of Symptoms: COVID-19, especially in severe cases, tends to cause more intense and prolonged symptoms, including severe respiratory complications such as pneumonia and acute respiratory distress syndrome (ARDS). While the flu can cause severe illness and complications, the overall severity is generally less compared to severe cases of COVID-19.
  • Onset of Symptoms: The incubation period for COVID-19 is generally longer than that of the flu. Symptoms of COVID-19 typically appear 2 to 14 days after exposure. Symptoms of the flu often develop within a few days after infection.

While the flu can come with respiratory issues and dampen a person’s senses, it's generally not to the degree of Covid. Both diseases can also be tested through a nasal or mouth swab. 

What is the peak time for colds?

Colds are more common during the fall and winter months. The peak time for colds often occurs from September to April in the Northern Hemisphere, with the highest incidence during the late fall and early winter. In the Southern Hemisphere, where seasons are reversed, the peak for colds typically occurs during the late fall and early winter months as well.

When is the most common time for flu?

Historically speaking, the most severe spikes for the flu occur in December and February. While the disease remains present year-round, it most often starts spreading aggressively in December and is heavily reduced at the end of March. 

What time of year is Covid most common? 

While our understanding of Covid-19 and its variants is relatively new compared to other conditions, we now understand that the disease displays seasonal trends, like the flu. More specifically, in the three years the virus has been present since the start of the pandemic, Covid-19 has shared the time of year it spreads most aggressively with the flu, with both spreading most aggressively between November and April. 

How CallonDoc can help

Treating online before the endemic where telemedicine erupted in popularity, Call-On-Doc has over 260,000+ 5-star reviews and offers quick, same-day treatment for all urgent care needs, including colds, flu, and covid seven days a week. Not only do we offer Paxlovid for those with Covid and multiple options for the common cold and the flu, but we also offer a doctor’s note for those who can’t go to work or need to isolate themselves!

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Wayne C. Hahne,

English graduate and Call-On-Doc’s medical resource guide, Wayne C. Hahne is an experienced and passionate medical education content expert. Through diligent research, provider interviews and utilizing the industry's leading resources for wellness information, it is Mr. Hahne’s personal mission to educate the general public on medical conditions with in-depth and easy-to-understand written guides.

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