Flu usually hits fast with a high temperature and an aching body, a cold builds slowly over two to three days, and COVID-19 can bring a fever and a new continuous cough, but the symptoms overlap so much that you cannot always tell them apart.
Quick Answer: Flu, Cold or COVID-19?
- Flu: sudden onset, often within a few hours, with a high temperature, an aching body and extreme tiredness
- Cold: builds gradually over 2 to 3 days, mainly a runny nose, sneezing and a sore throat; a high temperature is unusual
- COVID-19: can include a fever, a new continuous cough, tiredness, body aches and a change in taste or smell
- The symptoms overlap, so you cannot always tell them apart by symptoms alone
- Stay at home while you are unwell to protect vulnerable people
- Not sure what you have, or whether you are higher risk? Walk-ins are allowed at Rother Care Pharmacy, or call 01789 297596. If you have a high temperature, please call first.
Flu, Cold or COVID-19: The Key Differences
Flu, colds and COVID-19 are respiratory infections caused by different viruses that share many symptoms, so it helps to check how quickly symptoms started, whether you have a fever, and whether your taste or smell has changed.
How Fast Symptoms Start
The speed of onset is often the clearest early clue between flu and a cold. UKHSA says flu symptoms develop very rapidly, while cold symptoms come on gradually over 2 to 3 days. UKHSA does not give a typical speed of onset for COVID-19, so speed alone cannot separate it from flu.
Fever
A high temperature is a typical sign of flu, and some people with COVID-19 have a fever or chills. Colds do not usually cause a high temperature.
Tiredness and Body Aches
Extreme tiredness and an aching body are hallmark flu symptoms, and tiredness and body aches are also listed for COVID-19. A cold can leave you feeling tired and unwell with aching muscles, but the NHS notes you usually still feel well enough to do your normal activities.
Cough and Sore Throat
All three illnesses can cause a cough or a sore throat. The NHS lists a new continuous cough as a main COVID-19 symptom. UKHSA also notes that some people report a particularly painful sore throat with the latest COVID-19 variants, which the media has called razor-blade throat.
Change in Taste or Smell
The NHS lists a loss or change of smell or taste as a COVID-19 symptom. UKHSA also lists loss of taste and smell among cold symptoms, so it is a useful clue but not a reliable way to tell the illnesses apart on its own.
Quick Comparison Table
| Flu | Cold | COVID-19 | |
|---|---|---|---|
| Onset | Very rapid, often within hours | Gradual, over 2 to 3 days | No typical speed given by UKHSA |
| High temperature | Typical | Not usual | Can occur (fever or chills) |
| Tiredness | Extreme tiredness common | Feeling tired and unwell | Can occur |
| Body aches | Typical | Aching muscles can occur | Can occur |
| Cough | Can occur | Can occur | New continuous cough |
| Sore throat | Can occur | Can occur | Can occur, sometimes very painful |
| Change in taste or smell | Not listed by NHS | Can occur | Listed by NHS |
Based on UKHSA and NHS guidance. Symptoms overlap, so this table cannot diagnose which illness you have.
Why It Is Hard to Tell Them Apart
Flu and COVID-19 can be circulating at the same time in winter, and their symptoms overlap, which is why symptoms alone often cannot tell you which one you have. The NHS says most people do not need a rapid COVID-19 test. If you are unsure, or you are in a higher-risk group, ask your pharmacist, GP or NHS 111 for advice.
What to Do If You Think You Have Flu or COVID-19
Home care for flu and COVID-19 focuses on protecting other people and looking after yourself while you recover.
- Stay at home and avoid contact with other people while you have a high temperature or feel too unwell for your normal activities, especially anyone vulnerable
- Rest and sleep, and drink plenty of fluids to avoid dehydration
- Take paracetamol or ibuprofen to lower your temperature and ease aches and pains
When to Call NHS 111 or See a GP
Get urgent advice from NHS 111 or your GP if you have flu symptoms and any of the following, based on NHS guidance:
- You are worried about a baby’s or child’s symptoms
- You are 65 or over
- You are pregnant or have recently had a baby
- You have a long-term medical condition, such as diabetes or a heart, lung, liver, kidney, brain or nerve condition
- You have a weakened immune system
- You feel very unwell or short of breath
- Your symptoms have not improved after 7 days
Call 999 or go to A&E for sudden chest pain, severe difficulty breathing or coughing up blood.
The Best Protection: Get Vaccinated
Vaccination is the best protection against flu and COVID-19, and if you are in an eligible group both vaccines are free on the NHS and can be given at the same appointment. Read NHS Flu Vaccine Eligibility 2026/27: Who Gets a Free Jab? to check if you qualify, or see our Flu and COVID Season page for details, and our Flu Vaccination page to book.
Not Sure What You Have? Ask Our Pharmacist
If you are unsure what you have, or whether you are in a higher-risk group, Rother Care Pharmacy on Alcester Road, Stratford-upon-Avon can help. Walk-ins are allowed, or call us on 01789 297596. If you have a high temperature, please call first so we can advise you before you visit. You can also contact the team or book an appointment online.
Frequently Asked Questions
What is the biggest difference between flu and a cold?
Speed and severity. Flu comes on within a few hours and can leave you exhausted and too unwell to carry on as normal, while a cold builds gradually over a few days and usually leaves you well enough to do your normal activities.
Is a change in taste or smell a sign of COVID-19?
It is listed as a COVID-19 symptom by the NHS, but UKHSA also lists loss of taste and smell among cold symptoms, so it cannot tell you on its own which illness you have.
What is razor-blade throat?
UKHSA describes it as a particularly painful sore throat that some people report with the latest COVID-19 variants. The media has called it razor-blade throat.
Do I need a test to know which one I have?
The NHS says most people do not need a rapid COVID-19 test. Because the symptoms overlap, if you are unsure or in a higher-risk group, ask your pharmacist, GP or NHS 111 for advice.
How long should I stay at home?
Stay at home and avoid contact with other people while you have a high temperature or feel too unwell for your normal activities. If you test positive for COVID-19, the NHS says to try to stay at home for 3 days after the test if you are under 18, or 5 days if you are 18 or over.
Can I walk in to Rother Care Pharmacy if I am not sure what I have?
Yes, walk-ins are allowed at Rother Care Pharmacy and our pharmacist can give advice. If you have a high temperature, please call us on 01789 297596 first.
Medical disclaimer: this article is for general information only and is not a substitute for professional medical advice or a diagnosis. Speak to your pharmacist, GP or NHS 111 about your individual circumstances, and seek urgent help if your symptoms are severe. Guidance is correct as of September 2026 and may change.
Sources: UKHSA: do I have flu, COVID-19 or a cold?; NHS.uk: flu; NHS.uk: COVID-19 symptoms and what to do. Last updated 26 September 2026.