What People Get Wrong About Colds and Flu
Colds and Flu: what people commonly get wrong, set against what published UK guidance says.
Onset speed separates them in practice, and it matters because one of them has a vaccine and antivirals.
Key takeaways
- Cold onset: gradual, over 1-2 days
- Flu onset: abrupt, over hours
- Most useful single change: Have the annual flu vaccine if you are eligible.
- Commonest mistake: Asking for antibiotics, which do not work on viruses.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
What the guidance actually says
The numbers first, since the corrections only mean something against them.
| Measure | Figure |
|---|---|
| Cold onset | gradual, over 1-2 days |
| Flu onset | abrupt, over hours |
| Fever | uncommon in colds; common and above 38C in flu |
| Typical cold duration | about 7-10 days |
| Antiviral window for flu | usually within 48 hours of onset |
Where people go wrong
Each of these is common, and each is a mistake in the sense that the guidance says otherwise.
- Asking for antibiotics, which do not work on viruses
- Assuming last year's flu vaccine still protects you
- Giving aspirin to anyone under 16
What to do instead
- Have the annual flu vaccine if you are eligible
- Rest and keep fluids up; both are self-limiting in most people
- Stay away from others while you have a fever
- Contact a GP early if you are higher risk and think you have flu
The part that is genuinely uncertain
Guidance changes, and it changes because evidence does. The figures above reflect current UK guidance from the bodies named at the foot of this page; where those bodies revise their position, theirs is the account to follow rather than this one.
Where to go next
- Colds and Flu in Five Minutes
- Colds and Flu: What Published Guidance Supports
- Colds and Flu — the reference entry
- The Evidence on Antibiotics, Without the Hype
- What the Guidance Really Says About Hand Hygiene
When to speak to a doctor
Contact a GP or NHS 111 if you are over 65, pregnant, immunosuppressed, or have a long-term condition and develop flu symptoms. Call 999 for difficulty breathing, chest pain, coughing up blood, confusion, a rash that does not fade under pressure, or a child who is struggling to breathe, floppy or will not wake.
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, summarised or generalised 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 a GP, 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 999.
Spotted something wrong? Report an error on this page. We correct on the page and say what changed.
