Is it a cold, flu, RSV or COVID-19? Here’s how to tell the difference

Christopher Connolly, MD, is a board-certified internal medicine physician at Inova 360º Concierge Medicine with more than 24 years of clinical experience. Dr. Connolly previously served as the Medical Director and Chief Medical Information Officer of Nova Medical Group and Urgent Care. Most recently, Dr. Connolly worked as a primary care physician for Inova Primary Care in Ashburn and as a lead physician informaticist for Inova Primary Care.

It might start as a sniffle or a headache. You know you’re coming down with something — but what? Is it just a cold? Or could it be RSV, the flu or COVID-19? Do you need to call your doctor or just hit the couch?

You can often tell these viruses apart — if you know what to look for. From there, you can determine when you need to seek medical care.

Different viruses, different symptoms

At first glance, colds, flu, RSV and COVID-19 can look alike. All of them can start with symptoms that feel like a “head cold.” But a closer look reveals that these illnesses have some key differences.

Common cold symptoms

The mildest of these viruses, the common cold usually doesn’t require a doctor’s visit. You probably have a cold if your symptoms come on slowly and get worse over a period of 1 to 3 days.

Common cold symptoms usually include:

  • Cough, which can be dry or productive (coughing up phlegm)
  • Fatigue (typically mild)
  • Runny or stuffy nose
  • Sneezing
  • Sore or scratchy throat
  • Watery eyes

A cold will usually not cause:

  • Body aches
  • Headache
  • High fever
  • Loss of taste or smell
  • Wheezing

Signs of the flu

The flu tends to make people more miserable than a cold. One of the first signs that it’s not a cold is its sudden onset. Within hours, you go from feeling fine to feeling terrible. If you have the flu, your symptoms may include:

  • Body and muscle aches
  • Chills
  • Dry cough
  • Fatigue (often severe)
  • Headache
  • High fever up to 104 degrees Fahrenheit, which lasts up to 4 days
  • Lack of appetite
  • Vomiting or diarrhea (usually in children)

It’s less common for people with the flu to experience:

  • Productive cough
  • Stuffy or runny nose
  • Wheezing or trouble breathing

Spotting symptoms of RSV

Respiratory syncytial virus (RSV) feels like a common cold to most young, healthy adults. But it’s not “just a cold.” Thousands of people — mostly adults over age 65 and infants — are hospitalized or die each year from RSV.

Symptoms of RSV often come on in stages and last a total of 7 to 14 days. Healthy adults may experience cold-like symptoms such as:

  • Dry cough
  • Headache
  • Runny nose
  • Sneezing
  • Sore throat

Babies under 12 months of age and adults over age 65 may have more serious symptoms, including:

  • Barking cough
  • Cough with a lot of mucus
  • Fever
  • Irritability
  • Loss of appetite

RSV can become severe and cause trouble breathing, which can be life-threatening. Seek emergency medical care if you notice:

  • Blue lips or fingernails
  • Nostrils flaring
  • Rapid breathing
  • Wheezing

COVID-19 symptoms

The current COVID-19 variant causes gradual, cold-like symptoms in most people. But like RSV, COVID-19 can be serious in older adults and people with other medical conditions.

The most common symptoms of COVID-19 include:

  • Body and muscle aches
  • Cough
  • Diarrhea or vomiting
  • Fatigue
  • Fever and chills
  • Headache
  • Loss of taste or smell
  • Runny or stuffy nose
  • Sore throat

Loss of taste or smell is a telltale sign of COVID-19. This symptom is much less common with other illnesses.

When to recover at home

Most of the time, people recover from these infections on their own, but there are exceptions. RSV can be dangerous for infants and older adults. COVID-19 and flu are more serious for older adults and people with other health issues.

The best course of action with a mild virus is to stay home to avoid spreading the illness to others. If you don’t have other health conditions or a weakened immune system, you can:

  • Drink plenty of water or other non-caffeinated, non-alcoholic beverages
  • Rest as much as possible
  • Take over-the-counter acetaminophen or ibuprofen to relieve symptoms
  • Use nasal saline for a stuffy nose

If you’re concerned about any symptoms, don’t wait it out. Contact your primary care provider or head to an urgent care facility. Many medical offices offer telehealth visits so you can discuss your symptoms without leaving home.

When you need a test

Most medical offices can do rapid tests for COVID-19, the flu and RSV. Testing can be helpful because:

  • It tells your provider what kind of treatment you may need. For example, some people may benefit from antiviral medication for COVID-19 or the flu.
  • It helps you protect others. If you find out you have RSV and you plan to be around a baby, for example, you could reschedule your visit.

Consider testing if you:

  • Are over age 65
  • Have health conditions like diabetes, heart, lung or kidney disease, HIV or obesity
  • Will have contact with someone at risk of severe illness, such as a baby, older adult or immunocompromised person
  • Take immunosuppressant medications (medications that weaken the immune response)
  • Work in a daycare or nursing home

When it’s an emergency

No matter what virus you have, some symptoms always require immediate medical treatment. Get emergency care if you or your loved one has:

  • Bluish lips or fingernails
  • Chest pain
  • Dizziness
  • Fever over 103 degrees Fahrenheit
  • Sudden confusion
  • Trouble breathing
  • Wheezing

Stop illness before it starts

When it comes to any illness, prevention is critical. You can help reduce your risk of getting sick if you:

  • Avoid being around people who are currently sick
  • Get at least 7 hours of quality sleep each night
  • Wash your hands regularly, especially after using the bathroom and before eating or preparing food

But even with the most diligent handwashing, you can still be exposed to viruses. Help protect yourself by getting vaccinated against:

  • COVID-19: Vaccines protect against severe COVID-19 complications and lower your chances of getting long COVID. Vaccines are available for everyone 6 months and older, so talk with your provider to make sure you’re up-to-date.
  • Flu: The flu vaccine reduces the risk of serious illnesses and hospitalizations and may reduce the length of symptoms. Everyone 6 months and older should get an updated flu shot yearly to protect against current flu viruses. 
  • RSV: The RSV vaccine is available to anyone who is pregnant or at least 60 years of age. Getting the vaccine during pregnancy helps protect your newborn from RSV. Talk with your provider about whether this vaccine could benefit you.

Inova can help with any illness Everyone gets sick sometimes. No matter what level of care you need, Inova is here for you. We offer many convenient primary care locations across northern Virginia and beyond. For urgent needs, our Go-Health Urgent Care provides same-day, walk-in and virtual care. Our expert Emergency Care


  1. Christine on January 25, 2024 at 8:31 am

    Very informative. Thank you.

  2. Linda on January 27, 2024 at 9:05 am

    Wonderful information.

  3. William on January 27, 2024 at 1:04 pm

    6 months ago I (age 70) caught, perhaps, the common flu, it lasted almost two weeks. I made an appointment, but the appointment was a couple days after symptoms went away & I was deemed fine. Merely a couple days later I caught something more serious, perhaps RSV, lasting over two weeks, coughing up phlem (which I saved for analysis, but never got such done). During both bouts I tested negative for COVID. Anyway, I feel like getting the flu or RSV vaccine would be redundant – I wish I could be tested & learn which illnesses I’ve caught.

    • Matt on May 18, 2024 at 8:30 pm

      When I was a kid of 14, on Long Island, NY, I worked in a drug store delivering Rxs and stocking shelves. That was 1959. There was a large box of Sputum Cups in the upper level storage collecting dust. No one ever cam in to buy one. Too bad I didn’t save any when the Big Walgreens put the drug store out of business while I was still working there paying my way through college!

  4. Teresa on January 28, 2024 at 9:11 pm

    Great help in determining between illnesses

  5. Nancy on January 29, 2024 at 11:11 am

    I wish I had been feeling well enough to look at this e-mail earlier. My husband and I are 76 years old and recently went through what we are pretty sure was RSV. Our son who lives with us got it in early Dec, from an unknown source. He isolated as much as possible in his room. I came down with it Dec 26, and my husband started symptoms 5 days later. My son is now better after a second short reoccurance. I am now about 50% recovered and getting my energy back. My husband who is disabled by Lewy Body Dimensia is starting to get better. He had more fever than our son or I did. One night my husband’s fever broke and his jamas and bedding were drenched. We all have had “foggy brains” throughout.
    The thing we all noticed was how absolutely sticky (almost glue like) the mucus we had was–and I have not seen that noted elsewhere. My husband is still having jags of hard sneezing of 7-9 times, several times a day, enough to cause his eyes to get blood shot as well as fatigue him. This also populates his eyes with a white discharge that is very “burny” (but has been active for about 6 mo). Five eye doctors have assured us it is not infection. I am wondering if he has something else going on now and we should contact his doctor, or if these are within normal range of reactions? A wet wash cloth over his eyes for 5 minutes relieves the burning, but nothing seems to diminish the sneezing, which is continuing to increase in strength and frequency.

    • Michael on June 8, 2024 at 7:48 am

      I have something very similiar going on here, on the tail end of three weeks of similar eye issues.

      Did you figure out what it was?

  6. Mary on May 4, 2024 at 7:18 pm

    Very helpful information as Ive caught the common cold from my husband today (watery burning eyes only) and we both got our spring Covid booster this past week so hoping for a quick recovery. Havent had a cold in years. Thanks

  7. Betsy on June 27, 2024 at 3:08 pm

    Very fatigue, scratching throat, my head feels big pressure (not headache). I’ve had covid 3 times. Last time, contracted 2 weeks from my doctors office. I went for my annual, started feeling sick 2 days later (on a Saturday). Monday got call from doctor’s office that 2 staff members had COVID the day I was there. And more infected on Friday….

    I cannot get my energy up & never regained my lungs strength from first time covid in 2020. So since then always shortness of breath. Any one else feel like this after covid?

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