COVID-19, cold, allergies and the flu: What are the differences?
What's the difference between COVID-19 and the flu?
COVID-19 and the flu are both contagious respiratory diseases caused by viruses. COVID-19 is caused by the SARS-CoV-2 virus, while the flu is caused by influenza A and B viruses. These viruses spread in similar ways.
COVID-19 and the flu cause similar symptoms. The diseases can also cause no symptoms or mild or severe symptoms. Because of the similarities, it can be hard to diagnose which condition you have based on symptoms alone. Testing may be done to see if you have COVID-19 or the flu. You can also have both diseases at the same time. However, there are some differences.
| Symptom or sign | COVID-19 | Flu |
|---|---|---|
| Cough | Usually (dry) | Usually |
| Muscle aches | Usually | Usually |
| Tiredness | Usually | Usually |
| Sore throat | Usually | Usually |
| Runny or stuffy nose | Usually | Usually |
| Fever | Usually | Usually — not always |
| Nausea or vomiting | Sometimes | Sometimes (more common in children) |
| Diarrhea | Sometimes | Sometimes (more common in children) |
| Shortness of breath or difficulty breathing | Usually | Usually |
| New loss of taste or smell | Usually (early — often without a runny or stuffy nose) | Rarely |
COVID-19 symptoms generally appear two to 14 days after exposure to SARS-CoV-2. Flu symptoms usually appear about one to four days after exposure to an influenza virus.
COVID-19 can cause more-serious illnesses in some people than the flu. Also, COVID-19 can cause different complications than the flu, such as blood clots and multisystem inflammatory syndrome in children.
While there is only one antiviral treatment for COVID-19, there are several antiviral drugs that can be used to treat the flu. Also, you can get an annual flu vaccine to help reduce your risk of the flu. The flu vaccine can also reduce the severity of the flu and the risk of serious complications. The vaccine can be given as a shot or as a nasal spray.
