Flu vs cold: how to tell?
Last updated September 3, 2026.
Flu: sudden onset, high fever, chills, body aches, exhaustion, dry cough. Cold: gradual build, runny nose, sore throat, sneezing, mild or no fever, and you can still function. The stakes split them: flu hospitalizes and kills, especially the elderly, infants, pregnant women, and the chronically ill; colds are a nuisance. Action follows the answer: flu plus high-risk or severe means call a doctor within 48 hours of onset, because antivirals work best in that window; otherwise home care, rest, fluids, acetaminophen or ibuprofen, and distance from vulnerable household members during the first 3 days, when contagiousness peaks. Flu's ER flags: trouble breathing, chest pain, confusion, severe vomiting, standing dizziness, or fever that returns with a worsening cough (post-flu pneumonia). The prevention note: the annual flu shot does not stop every case, but it turns truck-hits into grazes, which is the entire case for getting it.
What to do
- Sudden, fever, aches, flattened: flu.
- Gradual, nose and throat, functional: cold.
- High-risk or severe flu: call within 48 hours for antivirals.
- Breathing trouble, chest pain, confusion: ER.
- Fever returns with worse cough: pneumonia check.
Related questions
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