Editor’s note: This article originally ran August 25, 2020, and was updated September 19, 2022, to reflect updated public health guidance.
You wake up with a headache and cough. Great. Is this COVID-19, a cold or the flu? It’s also allergy season, of course—the options feel endless.
“These conditions can be so similar that it’s tough to figure out what’s going on without COVID-19 or flu tests, or a doctor’s visit,” says UNC Health family medicine physician Dana Neutze, MD, PhD. “It’s important to know, because while allergies aren’t contagious, the viruses that cause colds, the flu and COVID-19 definitely are.”
So while you’ll probably need a test or doctor to know for sure, here are some signs that might lead to an answer.
Allergies (Allergic Rhinitis)
Millions of Americans suffer from seasonal allergies each year. Allergies occur when the immune system misidentifies typically harmless allergens as invading foreign substances and tries to fight them off. The congestion you experience is your immune system battling what it perceives as a danger.
Symptoms of allergies include:
- Sore throat
- Runny nose (usually clear mucus) or nasal congestion
- Itchy, watery eyes
You won’t have aches or a fever with allergies.
Colds and allergies have similar symptoms, so it can be hard to tell the conditions apart. However, there are a few differences.
Symptoms of colds include:
- Coughing (often bringing up mucus)
- Sore throat
- Runny nose (usually thicker, colored mucus) or nasal congestion
- Aches and pains
- Mild fever
One way to tell whether you have allergies or a cold is the duration of your symptoms. A cold should get better in a week to 10 days. Allergies don’t go away unless they are treated or you remove the trigger. For example, fall allergies often resolve when the weather turns colder.
Flu or COVID-19
COVID-19 and influenza (seasonal flu) have similar symptoms, as both are contagious, infectious respiratory illnesses, but different viruses cause them.
Both COVID-19 and flu can have varying degrees of signs and symptoms, ranging from no symptoms to severe symptoms. Common symptoms that COVID-19 and flu share include:
- Fever or feeling feverish/chills
- Shortness of breath or difficulty breathing
- Fatigue (tiredness)
- Sore throat
- Runny or stuffy nose
- Muscle pain or body aches
- Some people may have vomiting and diarrhea
- Lack of appetite
COVID-19 can sometimes, but not always, cause a loss of taste or smell, while the flu does not.
If you are experiencing symptoms that could be COVID-19 or the flu, get a PCR test at a clinic or testing site, or take an at-home rapid test. You might have to repeat at-home tests over several days to receive a positive result, even if you have COVID-19.
If you need treatment for COVID-19 or the flu, call or schedule an appointment with your primary care provider or visit an urgent care (it is helpful to call ahead if possible).
If you are having difficulty breathing, call 911 or seek immediate treatment at an emergency department.
If you have cold or flu-like symptoms, you should limit contact with other people, including family members, to decrease the spread of infection. Stay in separate rooms and wear a mask when this isn’t possible.
The best way to prevent severe disease from COVID-19 and the flu is to be vaccinated for each disease. You can receive a COVID-19 vaccine or booster shot and the flu vaccine at the same time.
If you’re concerned about cold, flu, allergy or COVID-19 symptoms, talk to your doctor. If you need a doctor, find one near you.