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Understanding the Differences Between Flu, Allergy, Cold, and COVID-19 Symptoms

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Richard S. Roberts, MD
Medically reviewed by
Richard S. Roberts, MD
Distinguishing between flu, allergy, cold, and COVID-19 symptoms is crucial for several reasons. First, knowing what you’re dealing with can help you ensure you’re effectively treating and managing your symptoms. Additionally, you’ll be able to avoid infecting others if you’re contagious. Not only can failing to treat the correct illness leave you suffering from symptoms for longer than necessary, but it can also put others at risk if you’re dealing with a cold or COVID rather than seasonal allergies. Below, we discuss more about distinguishing the differences between these ailments and how Carolina Asthma & Allergy Center can help you gain relief from unpleasant symptoms.

Allergy Symptoms

Allergies are immune responses to substances like pollen, pet dander, or certain foods. The most common symptoms include sneezing, itchy or watery eyes, nasal congestion, and skin rashes. 

Allergy symptoms, especially upper respiratory symptoms, can often mirror cold, flu, and COVID symptoms. However, there are a few key differences to consider.

  • Flu and COVID-19 may present with fever, body aches, and respiratory symptoms, but allergies do not. Meanwhile, shortness of breath is more indicative of COVID-19.
  • Colds share some symptoms with allergies, but allergies typically lack the sore throat and thick mucus characteristic of colds.

Allergies also tend to exhibit seasonal patterns. Pollen allergies, for example, may be at their worst during spring and fall. Understanding these variations can help you in identifying the root cause of symptoms.

Managing and Treating Allergies

There are a few strategies you can employ to ease the hold that allergy symptoms may have on your daily life.

  • Avoidance: Identifying and avoiding allergens is one of the key strategies in reducing symptoms. This can involve adjusting your outdoor activities during high pollen seasons or creating allergen-free environments at home (like using HEPA filters). 
  • Medications: Antihistamines, decongestants, and nasal corticosteroids can provide quick relief. Over-the-counter or prescription options are also available depending on how severe your symptoms are. 
  • Immunotherapy: For persistent allergies, immunotherapy (which can include allergy shots or tablets) can help desensitize the immune system to specific allergens, providing long-term relief.

Flu Symptoms

Influenza (or “the flu”) is an infectious respiratory illness caused by the influenza virus. Typical symptoms include fever, chills, cough, sore throat, muscle or body aches, fatigue, headache, and sometimes vomiting and diarrhea.

While flu symptoms can overlap with other respiratory illnesses, certain features set it apart:

  • Fever and body aches
  • The flu also tends to be more severe and sudden in onset, with a higher likelihood of complications.
  • Fever, cough, and fatigue are common to both the flu and COVID, but the loss of taste or smell and shortness of breath are more indicative of COVID-19.

Flu symptoms usually begin one to four days after you’ve been exposed to the virus. The length of the illness varies from person to person, but most people tend to recover within a week or two. However, fatigue and weakness can persist for several weeks.

Treating the Flu

Most mild cases of the flu can be managed through adequate rest, hydration, and over-the-counter medications to alleviate symptoms. 

Prescription antiviral drugs like oseltamivir (Tamiflu) may also be recommended, particularly for those at higher risk of complications or with severe symptoms. However, if you go this route, early treatment is crucial.

When to Seek Medical Attention for Flu Symptoms

Seek medical attention if your symptoms worsen, especially if you have any of the following symptoms: 

  • Difficulty breathing
  • Persistent chest pain or pressure
  • Confusion
  • Sudden dizziness
  • Severe vomiting

Also be on the lookout for any symptoms that temporarily improve and then return, especially with fever and a worse cough.

Cold Symptoms

The common cold is caused by viruses like rhinoviruses. Colds present with a distinct set of symptoms, including a runny or stuffy nose, sneezing, coughing, sore throat, and mild fatigue. Unlike the flu, the onset of cold symptoms is usually gradual and less severe.

  • While colds and the flu share some symptoms, the flu tends to have a more abrupt onset, higher fever, and more intense body aches.
  • Unlike allergies, colds often involve thick mucus production, a sore throat, and may be accompanied by a low-grade fever.
  • While both COVID-19 and colds can cause coughing and a sore throat, COVID-19 is more likely to involve shortness of breath, loss of taste or smell, and more severe respiratory symptoms.

Cold symptoms typically last for about a week, with the most severe symptoms occurring during the first few days. The common cold is generally mild, but it can lead to complications for young children or those with compromised immune systems.

Home Remedies and Treatments for the Common Cold

  • Rest and hydration: Getting plenty of rest and staying hydrated helps the body recover.
  • Over-the-counter medications: Antihistamines, decongestants, and pain relievers can alleviate symptoms but should be used according to package instructions.
  • Humidifiers: Adding moisture to the air can relieve nasal congestion.
  • Chicken soup: Grandma was right. Chicken soup may help soothe cold symptoms and reduce congestion. 

While time and rest are often the best healers, incorporating simple home remedies can provide relief and ease the discomfort of the common cold. 

COVID-19 Symptoms

The primary symptoms of COVID-19, an illness caused by the SARS-CoV-2 virus, can vary widely. Some of the most common symptoms include:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

COVID-19 and the flu share many symptoms, such as fever, cough, fatigue, and body aches. However, COVID-19 is more likely to cause shortness of breath and loss of taste or smell.

While allergies may cause symptoms like coughing and a sore throat, they rarely involve fever, and symptoms tend to be more chronic than the acute onset seen in COVID-19. Similarly, while COVID-19 and colds share symptoms like cough and sore throat, colds typically involve less severe respiratory symptoms.

COVID-19 symptoms can progress over the course of several days. Mild cases will generally improve on their own, but severe cases can lead to pneumonia and acute respiratory distress syndrome. It’s critical to keep a close eye out for symptoms that get worse, especially difficulty breathing. 

Guidance on Testing, Treatment, and When to Seek Medical Help


If you experience symptoms or have been in close contact with someone with COVID-19, you should be tested. This can help with early detection and prevent further transmission, especially to vulnerable populations like the immunocompromised and the elderly.


There are several antiviral treatments for COVID-19. Although these medications don’t get rid of the virus itself, they can lessen symptoms and speed your journey toward recovery. However, just like antiviral medications for the flu, it’s crucial to begin treatment as soon as you begin experiencing symptoms.

If you’ve had symptoms for a few days already or otherwise don’t qualify for antiviral treatment, supportive care like rest and hydration can help ease the most severe symptoms.

Medical Help

Seek medical attention if you experience difficulty breathing, persistent chest pain or pressure, confusion, inability to stay awake, or bluish lips or face. Additionally, if your symptoms worsen or do not improve, especially if you’re high-risk, you should promptly seek medical help.

Overlapping Symptoms and How to Tell Them Apart

Allergies, colds, flu, and COVID share overlapping symptoms but require different management and precautions. Here’s a breakdown of common symptoms and tips on telling them apart.


  • Allergies: Rarely associated with a persistent cough
  • Cold/Flu/COVID-19: Can present with a dry or productive cough

Sore Throat:

  • Allergies: Usually not a primary symptom
  • Cold/Flu/COVID-19: Common, can range from mild to severe


  • Allergies: Uncommon, but possible due to disrupted sleep
  • Cold/Flu/COVID-19: Common, often more severe with the flu or COVID-19


  • Allergies: Infrequent, but sinus headaches can occur
  • Cold/Flu/COVID-19: Common, especially with flu and COVID-19

Runny or Stuffy Nose:

  • Allergies: Common, often clear discharge
  • Cold/Flu/COVID-19: Common, may include colored mucus


  • Allergies: Rarely associated with fever
  • Cold/Flu/COVID-19: Common, especially with flu and COVID-19

Shortness of Breath:

  • Allergies: Uncommon
  • Cold/Flu/COVID-19: Can occur, more pronounced in COVID-19

There are also seasonal patterns that occur with both allergies and respiratory viruses. Each season brings with it different allergens—tree pollen in the spring, ragweed in late summer and early fall, and mold and dust mites in the winter. Meanwhile, cold, flu, and COVID viruses tend to spread most quickly during winter months, when people spend more time indoors. 

Testing plays a crucial role in accurately diagnosing these conditions, especially given the overlap in symptoms. Allergy testing can be diagnosed through skin or blood tests that measure the specific antibodies your body produces in response to allergens. COVID and the flu can be diagnosed through laboratory tests. Colds, meanwhile, are generally diagnosed through symptoms alone. 

Symptoms Allergies Flu Cold Covid
Watery Eyes

Preventative Measures and General Health Tips

There are a few steps you can take to reduce your risk of contracting a respiratory illness—and to reduce the severity of symptoms if you do fall ill.

First, it’s important to stay up-to-date with your flu and COVID-19 vaccines. Even if vaccination doesn’t prevent you from contracting a virus, it can help you avoid serious complications that might otherwise land you in the hospital.

Next, practice good hand and respiratory hygiene. Wash your hands frequently with soap and water for at least 20 seconds, and use hand sanitizer when soap is not available. Always cover your mouth and nose with a tissue or your elbow when coughing or sneezing, and dispose of tissues properly.

Unlike colds, the flu, and COVID, allergies aren’t contagious. However, there are still some steps you can take to reduce your allergy symptoms. 

  • Keep windows closed during high pollen seasons, use air purifiers, and regularly clean living spaces to minimize dust and mold.
  • Shower and change clothes after spending time outdoors to remove allergens.
  • Wash bedding regularly in hot water, and consider using allergen-proof mattresses and pillow covers.
  • If allergies persist, consult with an allergist to identify specific triggers and discuss appropriate treatment options, including medications or allergy shots.

Maintaining a healthy immune system is also important. Consume a well-balanced diet rich in fruits, vegetables, whole grains, and lean proteins. Nutrients like vitamins C and D, zinc, and antioxidants play a crucial role in supporting a healthy immune system.

Remember, these measures contribute not only to preventing illnesses but also to overall well-being. By adopting a proactive approach to health, you empower your body to better defend against infections and allergens.

In Closing

While allergies can present similar symptoms to colds, the flu, COVID-19, and other respiratory illnesses, there are some key differences—if you’re dealing with a fever, sore throat, or persistent cough, it’s safe to say you’re more likely facing a viral illness than an allergy attack. 

However, if your symptoms are leaving you mystified—or miserable— you can reach out to Carolina Asthma & Allergy Center for specific diagnosis and treatment recommendations. Remember, the sooner you seek professional medical advice, the sooner you can be on the road to recovery. Contact us online or by calling (704) 372-7900 to schedule an appointment.

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