Quick Answer
The "Truck" Test: If you feel like you were hit by a truck (sudden high fever, severe aches, exhaustion), it's likely the Flu.
If you are just annoying sniffles, a sore throat, and mild tiredness that got worse over a few days, it's likely a Cold.
Symptom Comparison Chart
| Symptom | Cold | Flu (Influenza) |
|---|---|---|
| Onset | Gradual (over days) | Sudden (within hours) |
| Fever | Rare (or mild) | High (100-102°F+) |
| Aches | Slight | Severe |
| Fatigue | Mild | Severe (can last weeks) |
| Sneezing | Common | Sometimes |
| Sore Throat | Common (early symptom) | Sometimes |
| Headache | Rare | Common |
Key Differences Explained
The Common Cold
Usually milder. You can often still go to work or school (though you should rest). Focus is on the nose and throat (runny nose, congestion).
The Flu
A serious systemic viral infection. It affects the whole body. It can lead to pneumonia and hospitalization, making it much more dangerous than a cold.
Medical Review
Reviewed by: Ricardo Hamilton, MD
Last Updated: December 15, 2025
Sources: CDC, NIAID