Comparing the Flu vs. COVID-19: Similarities, Differences, and What You Need to Know

In the midst of the COVID-19 pandemic, differentiating between common illnesses and the coronavirus has become a pressing concern for individuals and healthcare professionals alike. One of the most common points of confusion is distinguishing between the flu vs. COVID-19 due to their overlapping symptoms. In this comprehensive guide, we will delve into the similarities and differences in symptoms between COVID-19 and the flu. 

Symptom Similarities

The flu (influenza) and COVID-19 (SARS-CoV-2) share a range of symptoms, making it challenging to differentiate between the two based solely on how you feel. These common symptoms include the following:

Fever and Chills

Both illnesses can cause high fever and shivering, although the severity may vary.


A persistent dry cough can be a symptom of both the flu and COVID-19.


Feeling extremely tired is a common experience with both viruses.

Body Aches

Muscle and body aches are frequent complaints among those with either infection.


Severe headaches can occur in both cases, often accompanied by sinus congestion.

Sore Throat

Sore throats can be a symptom of either illness, though they tend to be more of a common flu symptom.

Shortness of Breath

Difficulty breathing may occur in both the flu and COVID-19, especially in severe cases.

woman with flu symptoms

Key Differences in Symptoms

While there are many symptom similarities between the flu and COVID-19, some key differences can help in distinguishing one from the other.

Loss of Taste and Smell

While this symptom can occur with the flu, it is more commonly associated with COVID-19. If you experience a sudden loss of taste and smell, it’s a strong indicator of COVID-19.

Gastrointestinal Symptoms

Nausea, vomiting, and diarrhea are more commonly seen in COVID-19 cases than in flu cases.

Timing of Symptoms

COVID-19 symptoms may appear 2-14 days after exposure, with an average incubation period of around five days. In contrast, the flu typically has a shorter incubation period of one to four days.


The flu is more likely to be seasonal, with outbreaks peaking in the fall and winter. COVID-19, on the other hand, can spread year-round.

Diagnosing the Flu and COVID-19

Given the symptom overlap, a definitive diagnosis of whether you have the flu or COVID-19 usually requires medical testing. Here are the primary methods for diagnosing these illnesses:

Molecular PCR Testing

Polymerase Chain Reaction (PCR) tests are the gold standard for diagnosing COVID-19. A swab sample is collected from the back of the throat or nose, then the virus’s genetic material is analyzed in a lab. This method provides highly accurate results.

Antigen Testing

Antigen tests for COVID-19 are quicker than PCR tests and can provide results within minutes. However, they are slightly less accurate and may yield false negatives.

Serological Testing

Serological tests, or antibody tests, can detect past COVID-19 infections by checking for the presence of antibodies in the blood. These tests are not used to diagnose current infections but can indicate if you’ve had COVID-19 in the past.

Rapid Influenza Diagnostic Tests (RIDTs)

For the flu, rapid tests similar to antigen tests are available. They can provide results in about 15 minutes, but their accuracy can vary, and negative results may require confirmation with a PCR test.

Clinical Assessment

In some cases, a healthcare provider may diagnose the flu or COVID-19 based on clinical assessment, especially when testing is not readily available. They will consider your symptoms, medical history, and exposure to known cases.

Why Accurate Diagnoses Matter


The treatments for the flu and COVID-19 differ, and an accurate diagnosis ensures you receive the appropriate care. Antiviral medications like Tamiflu are available for the flu, but there are no specific antiviral drugs or treatments for COVID-19.

Isolation and Quarantine

Accurate diagnosis helps in implementing the right isolation and quarantine measures, according to the Centers for Disease Control and Prevention (CDC), to prevent the spread of the respective virus.

Contact Tracing

It allows for effective contact tracing to notify individuals who may have been exposed to the virus, reducing further transmission. This can be important during flu season or a COVID-19 surge, especially if the people you interact with haven’t had their flu vaccine or any of the COVID-19 vaccines. 

Public Health Surveillance

Accurate data on the prevalence of each virus is essential for public health agencies to make informed decisions about disease control measures.

woman receiving a flu vaccine

Prevention Measures for Both Illnesses

Regardless of whether you have the flu or COVID-19, preventive measures are crucial:


Get vaccinated against both the flu and COVID-19. Vaccination significantly reduces the risk of infection and severe illness for both viruses.

Hand Hygiene

Regularly wash your hands with soap and water for at least 20 seconds or use hand sanitizer with at least 60% alcohol.


Wear a mask in indoor and crowded settings, as well as when you can’t maintain physical distance, especially during flu and COVID-19 outbreaks.

Physical Distancing

Maintain at least six feet of distance from others to reduce the risk of virus transmission.

Avoid Close Contact

Limit close contact with individuals who are sick, and if you are ill, stay home to prevent the spread of the virus.

doctor speaking with her patient

Flu vs. COVID-19 Treatment at Austin ER

In a world where the flu and COVID-19 now coexist, it’s vital to arm ourselves with the knowledge to make informed decisions about our health. While the similarities in symptoms between these viruses can be surprising, the differences, such as the sudden loss of taste and smell or when someone begins experiencing symptoms, can serve as crucial signs. Ultimately, obtaining an accurate diagnosis through medical testing is the best way to manage the impact of these illnesses.

In times of uncertainty, having a trusted partner in healthcare is invaluable. Austin ER offers help and support when you need it most. Our dedicated team of medical professionals is well-equipped to provide the necessary testing, care, and guidance to navigate the complex terrain of viral infections, ensuring that you receive the appropriate treatment and support.