In winter it is hard to tell whether a temperature and a cough are a cold, flu or COVID-19. The NHS page “COVID-19 symptoms and what to do” says the symptoms of COVID-19 are very similar to colds and flu, then sets out the symptoms, what to do at home, when to get help and how long to stay at home. Two points stand out: most people do not need a rapid lateral flow test when they have symptoms, and after a positive test you stay at home for 5 days if you are 18 or over, 3 days if you are under 18, counted after the day of the test. This sets out that page, with our notes added. It is UK guidance and may differ from Korean public-health advice.
1. Symptoms include a high temperature, a new continuous cough, a change to smell or taste, shortness of breath and tiredness — very similar to colds and flu.
2. Stay at home if you have a high temperature or don’t feel well enough for normal activities. After a positive test: 5 days if 18 or over, 3 days if under 18, and avoid people with a weakened immune system for 10 days.
3. Sudden chest pain, too breathless to speak in short sentences at rest, or coughing up blood: 999.
Symptoms — NHS
- A high temperature — feeling hot, cold or shivery, or your chest or back feeling hot to touch. The NHS says you do not need to measure your temperature.
- A new, continuous cough — coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours
- A loss or change to your sense of smell or taste
- Shortness of breath
- Feeling tired or exhausted
- An aching body
- A headache
- A sore throat
- A blocked or runny nose
- Loss of appetite
- Diarrhoea
- Feeling sick or being sick
The NHS says these symptoms are very similar to other illnesses such as colds and flu, and that most people feel better within a few weeks, though it can take longer. The “an hour” and “3 or more episodes in 24 hours” thresholds are how the page defines a new continuous cough.
Flu symptoms and how flu differs from a cold are in flu symptoms and flu or cold; checking and treating a high temperature at home is in high temperature in adults.
How long to stay at home — NHS
| Situation | What the NHS says | Worth noting (our gloss) |
|---|---|---|
| You have symptoms | Stay at home and avoid contact with others if you have a high temperature or don’t feel well enough for work, school, childcare or normal activities | Decided by how you feel, not by a test |
| Going back | Return to normal activities when you feel better or no longer have a high temperature | — |
| A child with mild symptoms | A child with only a runny nose, sore throat or mild cough who feels well enough can go to school or childcare | — |
| Positive — under 18 | Stay at home and avoid others for 3 days after the day of the test | Children and young people tend to be infectious for less time than adults, the page says |
| Positive — 18 or over | Stay at home and avoid others for 5 days after the day of the test | — |
| Positive — anyone | Avoid meeting people more likely to get seriously ill from infections, such as people with a weakened immune system, for 10 days after the day of the test | This 10 days still applies after the 5 or 3 |
On testing, the page says most people do not need a rapid lateral flow test when they have symptoms; if you choose to test and it is positive, follow the periods above. If you are eligible for COVID-19 treatments, take a rapid lateral flow test as soon as symptoms start — the page does not say who is eligible and points to a separate page.
What to do at home — NHS
| Type | What the NHS says | Worth noting (our gloss) |
|---|---|---|
| Do | Get lots of rest, drink plenty of water, take paracetamol or ibuprofen if you feel uncomfortable | — |
| Do | For a cough, a teaspoon of honey — but not for babies under 12 months | A pharmacist can advise on cough treatments |
| If breathless | Turn the heating down or open a window; breathe slowly in through your nose and out through your mouth with your lips together; sit upright in a chair; relax your shoulders; lean forward slightly with your hands on your knees or something stable | Cool the room, but not with a fan |
| Don’t | Lie on your back if you have a cough — lie on your side or sit upright | — |
| Don’t | Use a fan to cool the room — it may spread the virus | — |
| Don’t | Panic if you feel breathless — it can make it worse | The breathing tips above are the alternative |
Where to go — NHS
| Where | When | Worth noting (our gloss) |
|---|---|---|
| Urgent GP or 111 | You’re worried or not sure what to do; symptoms are getting worse or not improving | — |
| Urgent GP or 111 | Other signs of illness, such as a rash, loss of appetite or feeling weak | — |
| Urgent GP or 111 | A high temperature that lasts 5 days or more or doesn’t come down with paracetamol | — |
| Urgent GP or 111 | A child under 3 months with a temperature of 38C or higher, or 3 to 6 months with 39C or higher (or you think they have a high temperature) | Baby fever thresholds are also in baby fever |
| 999 or A&E | Seeming very unwell, getting worse, or you think something is seriously wrong — children and babies can get worse very quickly | — |
| 999 or A&E | Sudden chest pain | — |
| 999 or A&E | So breathless you are unable to say short sentences when resting, or breathing that has suddenly got worse — in babies the stomach may suck in under the ribs | Breathlessness in general: shortness of breath |
| 999 or A&E | Coughing up blood; collapsing or fainting; a seizure or fit for the first time | — |
| 999 or A&E | A rash that does not fade when you roll a glass over it — the same warning sign as meningitis | — |
999 is the UK emergency number and 111 the UK non-emergency health line; in Korea, read 119 for an ambulance (our reading). The NHS says getting help is especially important if you are pregnant, aged 60 or over, or have a weakened immune system.
Checklist
- ☐ High temperature, new continuous cough, change to smell or taste?
- ☐ Stay at home if you have a temperature or feel unwell
- ☐ After a positive test: 5 days if 18 or over, 3 days if under 18
- ☐ Avoid people with a weakened immune system for 10 days
- ☐ Don’t lie on your back with a cough; no fan
- ☐ Temperature for 5 days or more: get advice; chest pain, severe breathlessness or coughing up blood: 999
Questions that remain
Do I have to test if I have symptoms?
The NHS says most people do not need a rapid lateral flow test. Only people eligible for treatments are told to test as soon as symptoms start. We have not read how testing is advised in Korea.
When do the 5 or 3 days start?
The page says “after the day you took your test”, so we read it as counting from the next day (our reading).
What if I’m breathless without a temperature?
Being unable to say short sentences at rest, or breathing that suddenly gets worse, is listed as a 999 sign regardless of temperature.
More winter coughs and fevers on this site: common cold, cough, chest infection, pneumonia, the 2026 flu vaccine.
Sources
- NHS — COVID-19 symptoms and what to do — source (page shows: reviewed 21 March 2023, next review 21 March 2026; checked 10 November 2026 — the review date has passed and we quote the page as shown). The 12 symptoms, how long to stay at home (3, 5 and 10 days), testing, home care, 111 and 999 signs.
- Not read. The NHS pages on COVID-19 treatments and rapid lateral flow tests; Korea Disease Control and Prevention Agency guidance.
- What we added. The “worth noting” column, counting from the day after the test, the 119 reading.
Where else to check
- Korea Disease Control and Prevention Agency — Korean testing and isolation advice.
- A local clinic or pharmacy — if you’re worried, and for cough remedies.
Written on 10 November 2026. The content is from the NHS; the glosses are ours. It does not replace diagnosis or treatment.
