Written for Stock My Medicine and clinically reviewed by Hajra Dhanchora, MPharm (GPhC 2216990).
The quickest way to tell a cold from flu: a cold creeps, flu hits. A cold builds over a day or two and lets you carry on, grumbling. Flu arrives like a wall - often within hours - and puts you in bed. Here's how the two compare symptom by symptom, how long each really lasts, and what's worth taking from the pharmacy shelf.
Flu symptoms vs cold symptoms
Flu symptoms centre on your whole body: fever of 38°C or higher, aching muscles, exhaustion, headache, dry cough and shivers - with the runny nose almost an afterthought. Cold symptoms centre on your head: blocked or runny nose, sneezing, sore throat and a mild cough, usually with little or no fever in adults. The starkest tell is energy. With a cold you can work, badly. With flu, the walk to the kettle feels like a hike.
How long does a cold last?
Around 7–10 days, with the worst on days 2–3. The nose typically runs clear first, thickens mid-cold (that's normal, not automatically a sign of bacterial infection), then dries up. A lingering cough can trail on for up to three weeks after everything else has gone - annoying, but expected.
How long does flu last?
The fever and body aches usually break within 3–7 days, but flu's signature is the aftermath: tiredness that can drag on for two or three weeks. Going back to full speed too early is the classic flu mistake - your immune system spent serious resources, and it invoices you afterwards.
What to take for each
For a cold: a decongestant for the blocked nose by day, paracetamol or ibuprofen for the sore throat and heavy head, and honey and lemon is genuinely decent for the cough. For flu: regular paracetamol or ibuprofen for the fever and aches, fluids constantly, and sleep as medicine - a night-time formula like Night Nurse earns its keep when aches and cough keep you awake. Our cold, flu and cough range covers both camps - and one rule covers everything: never stack two paracetamol-containing products. Lemsip-style sachets, combination capsules and plain paracetamol all count towards the same daily limit.
Is "man flu" real?
Slightly, yes - and the joke may be backwards. There's evidence that testosterone dampens immune response, meaning men can experience genuinely worse viral symptoms than women with the same infection. What science gives with one hand it takes with the other: "worse symptoms" is not the same as "worse patient".
When it's neither - or when to get help
COVID, RSV and half a dozen other viruses share this territory; if it matters (vulnerable household, work rules), a combination test settles it. See a pharmacist or GP if a fever lasts beyond five days, breathing becomes wheezy or painful, one side of the chest hurts on breathing in, or a cold "comes back" worse after improving - that pattern can mean a secondary infection. For anyone pregnant, over 65, or with lung, heart or immune conditions: the free NHS flu jab is the single best cold-season decision, ideally in October.
Frequently asked questions
Can you have flu without a fever?
It's possible, especially in older adults - but body aches plus sudden exhaustion still point to flu rather than a cold.
Do antibiotics help a cold or flu?
No - both are viruses. Antibiotics do nothing except when a secondary bacterial infection (like sinusitis or a chest infection) develops on top.
Should I feed a cold and starve a fever?
Feed both, gently, and drink for ten. Fluids matter far more than food rules from the 1500s.