Conditions
Cold, flu, COVID-19 or allergies? How to tell the difference
A side-by-side symptom comparison of colds, flu, COVID-19 and seasonal allergies, when to test, who should seek early treatment and emergency warning signs.
Key takeaways
- Symptoms overlap, so a test is the only reliable way to tell flu and COVID-19 apart.
- Fever and body aches point away from allergies; itchy eyes point toward them.
- People at higher risk should contact a clinician early — antiviral medicines work best within days.
A runny nose and a sore throat could be a cold, the flu, COVID-19 or allergies. Knowing the likely cause helps you decide whether to rest at home, test, stay away from others or seek treatment.
Symptoms compared
| Symptom | Cold | Flu | COVID-19 | Allergies |
|---|---|---|---|---|
| Onset | Gradual | Sudden | Varies | Any time, often seasonal |
| Fever | Rare | Common | Common | No |
| Body aches | Mild | Common, often severe | Common | No |
| Tiredness | Mild | Common, can be extreme | Common | Sometimes |
| Sneezing | Common | Sometimes | Sometimes | Common |
| Itchy, watery eyes | Rare | Rare | Rare | Common |
| Loss of taste or smell | Sometimes, with congestion | Rare | Possible | Sometimes, with congestion |
| Typical duration | 7–10 days | 1–2 weeks | Varies | As long as exposure continues |
Testing
Home rapid tests for COVID-19, and combined COVID-19 and flu tests in some countries, give results in minutes. A negative rapid test early in illness may need repeating after a day or two. Clinics and pharmacies can also test.
Who should seek treatment early
Antiviral medicines for flu and COVID-19 work best when started within the first few days of symptoms. Contact a clinician promptly if you are 65 or older, pregnant, have a long-term condition such as heart or lung disease, diabetes or kidney disease, or have a weakened immune system. A telehealth visit is often the quickest route.
Feeling better at home
- Rest and drink plenty of fluids.
- Paracetamol (acetaminophen) or ibuprofen can ease fever and aches — follow the label.
- Honey can soothe a cough in adults and children over 1 year old.
- Antibiotics do not treat colds, flu or COVID-19, which are caused by viruses.
- For allergies, avoiding triggers, saline rinses and non-drowsy antihistamines or steroid nasal sprays help many people.
Get emergency care for difficulty breathing, chest pain or pressure, confusion, bluish lips or face, severe weakness, signs of dehydration, a seizure, or symptoms that improve and then return with fever and a worse cough.
Preventing spread
Stay home while you have a fever and until you feel better, wash your hands often, cover coughs and sneezes, and consider a mask around vulnerable people. Yearly flu vaccination and staying up to date with COVID-19 vaccination reduce the risk of severe illness. Watch WHO’s and HSE’s hand-hygiene videos in our video library.
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