Editor’s note: This article originally ran August 25, 2020, and was updated December 12, 2024.
You wake up with a headache and cough. Great. Is this COVID-19, a cold or the flu? It’s could also be allergies, 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 offer clues.
It Could Be Allergies
Millions of Americans suffer from seasonal allergies, or allergic rhinitis, 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:
- Sneezing
- Coughing
- Sore throat
- Runny nose (usually clear mucus) or nasal congestion
- Itchy, watery eyes
You won’t have aches or a fever with allergies.
It Could Be a Cold
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
- Fatigue
- Aches and pains
- Mild fever
You typically won’t have itchy, watery eyes with a cold. Another 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.
It Could Be 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.
The severity of both infections can vary widely, from no symptoms to severe symptoms. Common symptoms that COVID-19 and flu share include:
- Fever or feeling feverish/chills
- Cough
- Shortness of breath or difficulty breathing
- Fatigue
- Sore throat
- Runny or stuffy nose
- Muscle pain or body aches
- Headache
- Vomiting and diarrhea (in only some cases)
- Lack of appetite
COVID-19 can sometimes, but not always, cause a loss of taste or smell, which is less common with the flu.
If you are experiencing symptoms that could be COVID-19 or the flu, take an at-home test or see your provider to be tested.
If you need treatment for COVID-19 or the flu, schedule a virtual visit with your primary care provider. For COVID-19, they may prescribe Paxlovid, which can reduce your risk of a severe case. Antiviral drugs also are available to shorten the duration of the flu.
Both COVID-19 and the flu can cause severe illness and complications, particularly for older adults and people with underlying medical conditions. If you are having difficulty breathing, call 911 or seek immediate treatment at an emergency department.
If you have cold, COVID-19 or flu 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 that 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 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.