Is It Flu, A Cold, Allergies or COVID-19?

The overlap of COVID-19, colds, seasonal flu and allergies can present a challenge. Recognizing the symptoms unique to each can help differentiate them, especially symptoms between COVID-19 and flu. Each are contagious and can have serious risks to older adults and other medically vulnerable individuals. Although they present with similar symptoms, there are subtle differences.

Key Takeaways: COVID, Colds, Flu Or Allergies?

• Symptoms often overlap—but key differences matter. COVID-19, flu, cold, and allergies can share symptoms like cough, sore throat and runny nose, making them hard to distinguish at first glance.
  
• Shortness of breath can be a major COVID-19 warning sign. While many symptoms are similar to the flu, respiratory distress (difficulty breathing) is a key differentiator for COVID-19 and may signal more serious illness requiring medical attention.
  
• Flu hits fast and more intensely than a cold. Flu symptoms typically come on suddenly and include fever, body aches, fatigue, and headaches, whereas colds generally develop gradually and are milder.
  
• Itchy, watery eyes point to allergies, not viral infection. Allergy symptoms like itching (eyes, nose, throat) and clear nasal drainage are distinguishing signs that set them apart from viral illnesses like COVID-19 or the flu.

What Is A Cold?

Colds are infections of the upper respiratory tract (sinuses, nasal passages, throat and larynx). They are caused by several different viruses and are spread by touching a person with a cold, or touching object that someone with a cold has touched, or by breathing the virus in the air after someone with a cold has coughed or sneezed into the air.

Common cold symptoms may include:

• Stuffy, runny nose
• Scratchy, tickly throat
• Sneezing
• Watering eyes
• Low-grade fever
• Sore throat
• Mild hacking cough
• Achy muscles and bones
• Headache
• Mild fatigue
• Chills
• Watery discharge from nose that thickens and turns yellow or green

Colds usually start 2 to 3 days after the virus enters the body. Symptoms last from several days to several weeks.

How are seasonal allergies different from colds?

Seasonal allergies (hay fever) are caused by the immune system reacting to pollen from trees, grasses and weeds as if they were harmful to the body. This reaction causes symptoms that can be similar to a cold. Allergies often run in families. Seasonal allergies occur at the same time each year. If your child has allergy symptoms all year long, he or she may be allergic to things in the home, such as dust mites, animals, mold and cockroaches.

Allergies can cause itchy, watery eyes, which aren’t typical symptoms of a cold or flu.

Other common symptoms of seasonal allergies include:

• Sneezing
• Stuffy nose
• Runny nose
• Itchy nose, throat, eyes, and ears
• Nosebleeds
• Clear drainage from the nose

Usually, allergy symptoms last as long as you're exposed to the trigger.

What Are The Symptoms Of COVID-19 Coronavirus?

According to the Centers for Disease Control and Prevention (CDC), COVID-19 and flu share many symptoms but have a key differentiator: respiratory distress, which is marked by shortness of breath. This condition can lead to severe complications and can require hospitalization for oxygen therapy and other treatments, says Franciscan Physician Network provider Erica Kaufman West, MD, who specializes in infectious disease.

According to the World Health Organization, approximately 14% of COVID-19 patients require hospital admission. “About 5 percent end up in the intensive care unit because of shortness of breath,” says Dr. Kaufman West.

Other symptoms of COVID-19 can include:

• Body aches
• Chills
• Headaches
• Nausea or vomiting
• Runny nose
• Sore throats

“With COVID, if breathing gets difficult and the oxygen levels in the body drop, this can lead to increased fatigue and a higher chance of developing pneumonia,” says Dr. Kaufman West. Escalating symptoms, especially increasing difficulty in breathing to the point that engaging in simple activities becomes challenging, require immediate medical attention to assess oxygen levels and other critical factors.

Most people with COVID-19 will have milder symptoms, however, and can recover at home. According to the CDC, children with confirmed COVID-19 have generally presented with mild, cold-like symptoms, such as fever, runny nose and cough.

An essential development in the fight against COVID-19 is the availability of oral antiviral medications. These oral treatments are proving effective, particularly for individuals at high risk of severe illness.

“We have the IV medication for hospitalized patients, and that’s been there for a long time, but now we have pills we can give, and there are two different oral antiviral medications that are out there for patients with COVID,” Dr. Kaufman West says. “They both seem to be still effective against these new variants, maybe a little bit less effective, but still very good for preventing mortality and death. So, that endpoint remains an effective endpoint.

What Are The Symptoms Of The Flu?

Many flu signs overlap with symptoms of the common cold. However, there are some key differences, such as:

• Flu comes on all at once, while a cold gradually worsens.
• You’re not likely to have a fever with a cold, but you are with flu (although not always). You might also experience chills.
• You’ll have more intense muscle and body aches with the flu.
• Typically, a cold doesn’t cause headaches, but the flu does.
• You’ll feel noticeably tired and weak with the flu.

You may also experience a cough, sore throat, or a runny or stuffy nose. Vomiting and diarrhea are possible signs of flu, too, although this is more common in children than adults.

Preventive Measures And Testing For Flu, COVID & Allergies

Given the symptom overlap, health authorities stress the importance of vaccination as a primary preventive measure for flu and COVID-19. Vaccination can significantly reduce the severity of symptoms and the risk of complications. Additionally, regular testing for COVID-19, if symptoms are present or you’ve been exposed, remains a key recommendation to prevent the spread, especially to those at higher risk.

Another aspect of COVID-19 is "Long COVID," where symptoms persist for weeks or months beyond the initial infection. Recognizing these prolonged effects is important for seeking ongoing care and support. Unlike flu or allergies, Long COVID highlights the virus’s potential for lasting impact, making early detection and treatment even more essential.

Understanding the slight differences between COVID-19, flu, and allergy symptoms is key to managing your health. By staying informed, getting vaccinated and practicing preventive health measures, individuals can better navigate their symptoms and when to seek care. Always talk to your healthcare provider for guidance tailored to your specific situation.