Flu vs. COVID-19: How to Spot the Difference
As flu season overlaps with ongoing cases of COVID-19, many people wonder how to differentiate between the two illnesses. Both respiratory infections share overlapping symptoms, but there are also key differences that can help you identify what you may be dealing with. This guide will help you understand the distinctions and know when to seek medical advice.
By Dr. Daniel Sorli, MD
Similarities Between Flu and COVID-19
Flu (influenza) and COVID-19 are caused by different viruses—flu by the influenza virus and COVID-19 by the SARS-CoV-2 virus. Despite this, they share many symptoms, including:
- Fever or chills
- Cough
- Fatigue
- Muscle or body aches
- Sore throat
- Runny or stuffy nose
- Headache
Both can range from mild to severe and, in some cases, lead to complications such as pneumonia or hospitalization.
Key Differences in Symptoms
1. Onset of Symptoms
- Flu: Symptoms typically appear suddenly and are noticeable within 1–4 days of exposure.
- COVID-19: Symptoms often develop more gradually and may take 2–14 days after exposure to appear.
2. Fever
- Flu: High fever is a hallmark of influenza and often comes on quickly.
- COVID-19: Fever is common but not universal in COVID-19 cases and may not be as high as in flu.
3. Loss of Taste or Smell
- Flu: Rarely affects taste or smell.
- COVID-19: A sudden loss of taste or smell is a distinctive symptom of COVID-19 and can occur even in mild cases.
4. Cough
• Flu: The cough is usually dry but not as persistent.
• COVID-19: Persistent, dry cough is one of the hallmark symptoms.
5. Breathing Difficulty
- Flu: Shortness of breath is less common and typically occurs only if the flu progresses to complications like pneumonia.
- COVID-19: Difficulty breathing is more common, especially in moderate to severe cases, and should prompt immediate medical attention.
When to Seek Medical Advice
Regardless of whether you suspect flu or COVID-19, some symptoms warrant prompt medical attention:
- Difficulty breathing or shortness of breath
- Persistent chest pain or pressure
- Confusion or inability to stay awake
- Bluish lips or face
- Severe dehydration (e.g., no urination, extreme weakness)
If you’re experiencing mild symptoms but are unsure whether they are flu or COVID-19, consider a telehealth consultation or at-home COVID-19 testing as a first step.
Testing is Crucial
Because of the overlap in symptoms, testing is the only reliable way to distinguish between flu and COVID-19. Rapid tests are available for both illnesses, and your healthcare provider may recommend testing if symptoms are unclear or if treatment is time-sensitive.
Prevention: A Dual Approach
1. Vaccination
- Flu Vaccine: Get the flu shot annually to protect against the most common strains.
- COVID-19 Vaccine and Boosters: Stay up to date on COVID-19 vaccines and boosters to reduce the risk of severe illness.
2. Hygiene Practices
- Wash hands frequently with soap and water for at least 20 seconds.
- Avoid touching your face, especially your eyes, nose, and mouth.
- Cover your mouth and nose with a tissue or elbow when coughing or sneezing.
3. Masking and Social Distancing
- Masks and distancing are effective at reducing the spread of both flu and COVID-19, especially in crowded or high-risk settings.
Final Thoughts
Flu and COVID-19 are both serious illnesses, but understanding their differences can help you take the right steps to protect yourself and others. If you experience symptoms of either, don’t hesitate to seek testing and follow medical advice. Prevention is always better than cure, so stay vaccinated, practice good hygiene, and prioritize your health this season.
Stay safe and healthy,
Dr. Daniel