Is It a Cold, the Flu, Allergies, or COVID-19? Comparing Symptoms of Common Respiratory Illnesses.

Caesar Djavaherian, MD, MS, FACEP
October 5, 2021
4.5 mins

These days, common symptoms of respiratory illnesses can be very worrisome. A simple headache or stuffy nose can cause a lot of anxiety, and no one wants to be that person on the bus who’s coughing and sneezing into their mask!  

In the era of COVID-19, we’ve all become very cautious, and rightfully so. However, even though the common cold, the flu, allergies, and COVID-19 have similar symptoms, they are not the same. Understanding which symptoms are common with each illness will help us determine when we need to see a doctor, and when we can stay home and treat ourselves with over-the-counter medication and home remedies.

(If you have any questions about your symptoms or think you may have contracted COVID-19, make an appointment to talk to a healthcare provider who can assess your situation. Carbon Health offers  convenient same-day virtual appointments, so you can get the information you need, fast.)  

The Common Cold

The common cold is a mild condition that primarily affects the nose and throat. They are, indeed, very common (hence the name) in both children and adults — and an otherwise healthy adult can expect to have an average of two to three colds per year. Colds occur most often in the spring and winter, but you can get one at any time.

Some of the typical signs and symptoms associated with the common cold include:

     • Sore throat

     • Runny nose

     • Coughing

     • Sneezing

Some people also experience headaches and body aches. (It’s not uncommon to experience these general aches and pains with a cold, especially if you’ve been coughing a lot.)

Most people recover from the common cold in less than two weeks. If you have a weakened immune system or a respiratory condition like asthma, monitor your symptoms carefully. Seek medical attention if you have unusually severe symptoms, or if your symptoms are still present after 10 days.

The Flu 

Influenza (more colloquially called the flu) is a contagious illness that is usually mild but can lead to serious complications. In a healthy adult, the flu typically lasts for anywhere from a few days to up to two weeks at the most. Unlike the common cold, which usually develops gradually, most cases of the flu come on very quickly.

Some common symptoms include:

     • Fever (usually for three to four days)

     • Cough

     • Sore throat

     • Headaches

     • Fatigue

Some people may also experience vomiting or diarrhea. If you experience dizziness, confusion, seizures, shortness of breath, or severe weakness, you should seek medical attention right away.

One of the reasons that the flu is so dangerous is that it can lead to complications, causing serious illnesses like pneumonia, encephalitis, or even organ failure. To reduce your risk for complications, make sure to get your annual flu vaccine. The vaccine may not entirely prevent you from getting the flu, but it can make your symptoms much milder and decrease your risk for complications if you do get sick.


An allergy is a condition that occurs when your body reacts to something that is not truly a threat. That thing that triggers your symptoms is called an allergen. Many allergens are foods, but some of the most common are respiratory. This means that allergy symptoms are triggered when a person inhales the allergen.

Some of the most common airborne allergens include hay, pet dander, mold, pollen, and grass. For this reason, allergies tend to be worse in the spring and the summer, when plants are blooming.

Some of the most common airborne allergy symptoms include:

     • Itchy, watery eyes

     • Runny nose or congestion

     • Sneezing

     • Fatigue

Some people may also experience coughing, headaches, and shortness of breath.

Most of the time, symptoms abate soon after the exposure stops. Even though they can be frustrating, most respiratory allergy symptoms are mild and not a cause for concern.

You can help improve your symptoms by investing in an air purifier, wearing a mask, washing sheets and pillowcases frequently, and limiting your time outdoors, especially if it’s a windy day. You may also be able to treat symptoms with over-the-counter medication, such as nasal spray.


With more than 233 million cases of COVID-19 reported and 4.77 million deaths as of this writing, it’s understandable that any unusual symptoms affecting the respiratory system can be cause for alarm. The good news is that we have highly effective vaccines for COVID-19 — they greatly reduce not only your risk of catching the disease but also your risk of developing severe or life-threatening complications. 

While symptoms of COVID-19 are similar to those of other respiratory illnesses such as the common cold or the flu, there are a few important differences. A wide range of symptoms has been reported by people with COVID-19, but some of the most common are:

     • Fever

     • Cough

     • Sore throat

     • Stuffy or runny nose

     • Shortness of breath

     • Fatigue

     • Muscle or body aches

     • New or unexplained loss of taste or smell

Some people also experience nausea, vomiting, and diarrhea. Since there are so many symptoms that overlap with those of the common cold and the flu, it’s wise to get a COVID-19 test to ensure an accurate diagnosis.

Depending on your overall health, as well as the strain of COVID you contract, you may be at risk for developing serious symptoms and complications. You should seek immediate medical attention if you experience difficulty breathing, chest pain, dizziness, fainting, or an inability to keep fluids down. 

Not Sure Why You’re Feeling Sick? Make an Appointment with a Doctor.

If you’re experiencing a cough, runny nose, or sore throat, these symptoms are common to several different respiratory illnesses. To help you identify which one you have, it’s a good idea to consult a doctor. They can help evaluate your symptoms and recommend treatment options that will get you back to feeling normal in no time. In the meantime, make sure to rest, drink plenty of fluids, and wash your hands regularly to prevent the spread of illness. If you know you have been exposed to COVID-19, you should quarantine until you get a negative test result (the test should be taken 3 to 5 days after exposure for the most accurate results). 

Need to make an appointment? Visit or download the Carbon Health app and book a virtual or in-person visit with one of our healthcare professionals today.  

Carbon Health’s medical content is reviewed and approved by healthcare professionals before it is published, but it is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Talk to your healthcare provider about questions you may have regarding your health or a medical condition, and before making changes to your healthcare routine.

Editorial note: On December 27, 2021, the CDC (U.S. Centers for Disease Control and Prevention) updated their recommendations for quarantining and isolating after exposure to the virus that causes COVID-19. In a statement, the CDC announced, “People with COVID-19 should isolate for 5 days and if they are asymptomatic or their symptoms are resolving (without fever for 24 hours), follow that by 5 days of wearing a mask when around others to minimize the risk of infecting people they encounter. The change is motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after.” Read the full announcement.

Caesar Djavaherian, MD, MS, FACEP

As Carbon Health’s Chief Innovation Officer, Caesar Djavaherian, MD, MS, FACEP, guides clinical innovation through product development, service expansion, and partnerships with transformative companies working to improve the healthcare ecosystem. He is an emergency medicine physician, a former high school teacher, and a reformed academic researcher. Caesar co-founded Direct Urgent Care to deliver technology-enabled urgent care throughout the San Francisco Bay Area. He has practiced at New York-Presbyterian Hospital, the University Hospital of Columbia, and Weill Cornell Medicine. In his spare time, Caesar advises healthcare startups, cheers on the Warriors, tries various HIIT workouts, and daydreams about what the future of health will look like.