Flu vs Cold: How to Tell the Difference & When to See an Online Doctor
Educational information — not medical advice.
This article was prepared by the OnlineDoctor24 editorial team and reviewed for factual accuracy against UK clinical guidance (NHS and NICE). It is not written by a doctor and does not replace personal medical advice. For symptoms specific to you, book an online doctor consultation.
Key points
- Flu typically comes on suddenly with high fever and body aches; colds come on gradually with runny nose and sneezing.
- Most healthy adults recover at home with rest and fluids.
- Antivirals (oseltamivir / Tamiflu) can shorten flu if started within 48 hours, particularly in high-risk groups.
- See a GP urgently if breathless, very unwell, or in a high-risk category.
- Annual flu vaccination is the best prevention.
Key differences
| Symptom | Flu | Cold |
|---|---|---|
| Onset | Sudden (hours) | Gradual (1–2 days) |
| Fever | High, often >38.5°C | Mild or none |
| Body aches | Severe | Mild |
| Tiredness | Profound, may last weeks | Mild |
| Runny nose / sneezing | Sometimes | Common |
| Cough | Often dry | Mild |
Self-care
- Rest, fluids and paracetamol or ibuprofen for fever and aches.
- Stay home to avoid spreading illness.
- Honey and warm drinks for cough relief.
- Most people recover in 7–10 days, with tiredness lingering longer after flu.
Antivirals for flu
Oseltamivir (Tamiflu) and zanamivir can shorten flu by about a day if started within 48 hours of symptom onset. They are particularly useful for people at higher risk: pregnant women, over-65s, people with chronic lung, heart or kidney disease, diabetes, or weakened immune systems. An online GP can assess and prescribe.
When to see an online doctor
- You are in a high-risk group and have flu symptoms.
- Symptoms last more than 7–10 days or worsen after improvement.
- You need a sick note.
- You are uncertain whether it is flu, COVID-19 or something else.
Red flags — when to seek urgent help
Call 999 or go to A&E if you experience any of the following:
- Severe breathlessness or chest pain
- Coughing up blood
- Confusion or drowsiness
- Persistent high fever despite paracetamol/ibuprofen
- Symptoms worsening after initial improvement
Frequently asked questions
Common questions UK patients ask about influenza and common cold.
How an online doctor can help
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This article is for general information only and does not replace personal medical advice from a qualified doctor. Content is reviewed against UK NHS and NICE guidance by the OnlineDoctor24 editorial team and is not authored by a medical doctor. If your symptoms worsen or you are unsure, please book a consultation with a GMC-registered GP.
See a UK GP about this today
Same-day video or phone consultations with GMC-registered GPs. Prescriptions, sick notes and referrals when clinically appropriate.