Flu Versus a Cold: Common Questions
How to tell influenza, a potentially serious viral illness, from a common cold caused by other respiratory viruses.
Last revised
Flu Versus a Cold: the questions people actually ask, answered from published guidance.
Key takeaways
- Flu onset: sudden: fever, chills, body aches, headache and exhaustion
- Cold onset: gradual: runny or stuffy nose, sneezing and sore throat
- Most useful single change: Get a flu vaccine every fall.
- Commonest mistake: Antibiotics for a cold or flu; they do not treat viruses.
- See a doctor if any of the signs under "When to get help" below apply to you.
What is Flu Versus a Cold?
How to tell influenza, a potentially serious viral illness, from a common cold caused by other respiratory viruses.
Why does it matter?
Flu can lead to pneumonia and hospitalization, and antiviral medicines for flu work best when started early, so knowing the difference affects when to call a doctor.
Flu onset for Flu Versus a Cold?
Sudden: fever, chills, body aches, headache and exhaustion.
Cold onset for Flu Versus a Cold?
Gradual: runny or stuffy nose, sneezing and sore throat.
Flu antiviral medicine for Flu Versus a Cold?
Works best started within 48 hours of symptoms.
Yearly flu vaccine for Flu Versus a Cold?
Everyone 6 months and older, ideally by the end of October.
What is the single most useful thing to do?
Get a flu vaccine every fall.
What is the most common mistake?
Antibiotics for a cold or flu; they do not treat viruses.
When should I see a doctor?
Call your doctor if symptoms improve then return with fever and a worse cough, or if a cold lasts more than 10 days. Call 911 for difficulty breathing, chest or belly pain or pressure, new confusion, seizures, severe dehydration, or in a child, fast breathing, bluish lips or face, or ribs pulling in with each breath.
Related topics
- Colds and Flu: What Published Guidance Supports (Immunity)
- The Evidence on Pneumonia, Without the Hype (Respiratory Health)
- The Evidence on Vaccination in Older Adults, Without the Hype (Healthy Aging)
- Common Childhood Infections: What the Evidence Actually Says (Children's Health)
Where to go next
- The First Steps With Flu Versus a Cold
- Answers to the Common Questions on Flu Versus a Cold
- Flu Versus a Cold — the reference entry
- Infectious Diseases: The Complete Guide
- Measles: What the Evidence Actually Says
- Lyme Disease and Ticks: What Published Guidance Supports
When to get help
Call your doctor if symptoms improve then return with fever and a worse cough, or if a cold lasts more than 10 days. Call 911 for difficulty breathing, chest or belly pain or pressure, new confusion, seizures, severe dehydration, or in a child, fast breathing, bluish lips or face, or ribs pulling in with each breath.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
