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Summary: I separate cold-season fact from folklore so you know what truly prevents colds, what (slightly) shortens them, what eases symptoms—and what to skip. Save money, feel better, and keep it simple.

What we cover

• How common colds are and how long they last (2–3 per year on average; usually 5–7 days; cough can linger).

Prevention audit: 

• Vitamin C doesn’t prevent colds in the general population (Cochrane), though it helped in physically stressed groups; 
• handwashing probably helps (Cochrane) 
• echinacea doesn’t pan out (Cochrane) 
• garlic didn’t reduce colds but modestly reduced severity in one RCT (trial)
•  gargling showed a very small signal (trial)
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Grandma’s wisdom check: 

• Short sleep (<6 hours) quadrupled cold risk in a viral-challenge study (study) 
• cold exposure might matter (foot-chilling RCT: more colds in the chilled group, study
• lab data suggest colder noses weaken first-line defenses (mechanism)

Shortening a cold: 

• Vitamin C doesn’t shorten it when started after symptoms (Cochrane
• zinc lozenges can trim 1–2 days if started within 24 hours (≈100 mg/day elemental zinc in trials, meta-analysis
• chicken soup has plausible lab effects on white blood cells (study

Symptom relief: 

• Oral phenylephrine doesn’t work; the FDA voted 16–0 that it’s ineffective (FDA review
• Pseudoephedrine (the “real” Sudafed, behind the pharmacy counter) reduces congestion with meaningful effect sizes (evidence
• Honey 30 minutes before bed improved cough and sleep in kids (not for <1 year) and is supported by a broader review (RCTsystematic review 
• Humidifiers didn’t show clear benefit in trials (Cochrane
• Voice myth: Whispering actually stresses the vocal cords more for many people—so speak softly instead (study
• Flu vs. cold: Tamiflu is only for influenza and must be started within ~48 hours.

Takeaways

• To avoid colds: prioritize sleep and handwashing; keeping warm may help.
• To shorten a cold: consider zinc (start early). Chicken sou