Fine in the morning, then by the afternoon a sudden fever and aching all over — that points to flu more than a cold. The UK National Health Service (NHS) says flu often gets better on its own but can make some people seriously ill, and urges the flu vaccine if you’re advised to have it. Symptoms, how it differs from a cold, treatment at home and when to get help — as the NHS sets them out.
1. Flu appears within a few hours; a cold builds over 1 to 2 days.
2. Not improving after 7 days? Urgent GP appointment or 111 — the same if you’re 65 or over or pregnant.
3. Most infectious in the first 5 days. Germs live on hands and surfaces for around 24 hours.
Symptoms — NHS
| Type | What the NHS says | Worth noting (ours) |
|---|---|---|
| Onset | Symptoms come on quickly | — |
| Fever and body | Sudden high temperature, aching body, tiredness or exhaustion | — |
| Throat and cough | Dry cough, sore throat | — |
| Other | Headache, difficulty sleeping, loss of appetite | — |
| Children | Similar, plus ear pain, sore eyes, swollen glands, appearing less active | — |
Flu or cold — the NHS table
| Flu | Cold | |
|---|---|---|
| Onset | Appears within a few hours | Appears gradually over 1 to 2 days |
| Where | Affects more than nose and throat | Mainly nose and throat |
| How you feel | Exhausted and too unwell to carry on as normal | Unwell but well enough for normal activities |
The CDC’s version of the comparison is in flu vs cold.
Treatment at home — NHS
| Type | What the NHS says | Worth noting (ours) |
|---|---|---|
| Rest | Rest and sleep | — |
| Fever and aches | Paracetamol or ibuprofen; check it suits children, ask a pharmacist or GP if unsure | — |
| Fluids | Plenty of fluids to avoid dehydration | Pale urine is a good sign (ours) |
| Don’t | No aspirin for under-16s; don’t combine paracetamol with other remedies containing it | Read combination cold-remedy labels (ours) |
| Antibiotics | Don’t work for viral infections like flu; not recommended | — |
| Pharmacist | Can give treatment advice and recommend flu remedies | In Korea, ask at a pharmacy (ours) |
When to get help — NHS
| If | Where | Worth noting (ours) |
|---|---|---|
| Worried about a baby’s or child’s symptoms | Urgent GP appointment or 111 | — |
| 65 or over | Urgent GP appointment or 111 | Age alone |
| Pregnant or recently given birth | Urgent GP appointment or 111 | — |
| Long-term condition or weakened immune system | Urgent GP appointment or 111 | Diabetes, heart or lung disease, for example (ours) |
| Very unwell or short of breath | Urgent GP appointment or 111 | — |
| No improvement after 7 days | Urgent GP appointment or 111 | Count from the first day of symptoms (ours) |
| Sudden chest pain, severe difficulty breathing, coughing up blood | 999 or A&E; don’t drive yourself, bring your medicines | 119 in Korea (ours) |
Stopping it spreading — NHS
The NHS says flu is most infectious in the first 5 days and flu germs can live on hands and surfaces for around 24 hours. Wash hands often, catch coughs and sneezes in tissues, bin them quickly, and stay at home with a high temperature or if you don’t feel well enough for normal activities. 24 hours is a full day (our conversion) — worth wiping door handles and phones.
Vaccine — NHS
Every autumn or early winter the NHS offers the flu vaccine to adults and children at higher risk of serious flu. Korea’s schedule and free groups are in flu vaccine 2026.
Checklist
- ☐ Did it start suddenly, within hours?
- ☐ Rest, fluids, paracetamol or ibuprofen
- ☐ No aspirin under 16; watch for doubled ingredients
- ☐ 65+, pregnant or a long-term condition: get help early
- ☐ No better after 7 days: get help; chest pain, breathlessness or blood: emergency
- ☐ Limit contact, especially in the first 5 days
Questions that remain
How long does flu last?
The page gives no recovery time. It says to get help if symptoms don’t improve after 7 days.
What about antivirals such as Tamiflu?
The page doesn’t mention antivirals; it only says antibiotics don’t work. Prescribing is for a clinician (our note).
Sources
- NHS — Flu — source (page shows: reviewed 3 February 2026, next review due 3 February 2029; checked 22 October 2026). Symptoms (including children), the cold-vs-flu table, treatment at home, pharmacists, urgent GP and 111 criteria, 999 and A&E criteria, preventing spread, the vaccine.
- Not read. The hand-washing video; Korean flu treatment guidance.
- What we added. The “worth noting” column and the Korean care gloss.
Where to check further
- A pharmacy or local clinic — medicines and care.
Written on 22 October 2026. The content is from the NHS; the glosses are ours.
