“Airborne and Emergen-C prevent colds.”

“Elderberry prevents colds or influenza.”

Elderberry has not been shown to prevent colds or flu, and the only prevention trial found no clear drop in colds.

“Elderberry shortens colds or influenza.”

Elderberry has not been shown to shorten colds or flu, and the most careful flu trial found no difference in recovery time.

“Echinacea prevents colds.”

Echinacea does not reliably keep colds away; in pooled trials, people taking it were only slightly less likely to catch one.

“Honey eases coughs in children.”

For children 1 year and older, a spoonful of honey eases cough a little better than no treatment or a placebo, mostly for a night or two.

“Saline nasal rinses help you get over a cold faster.”

Salt water in the nose has not been shown to help colds end sooner; two early trials from one team reported faster recovery, but neither used a placebo.

“Vitamin D supplements prevent colds and flu.”

Vitamin D pills do not prevent colds or flu: across 40 trials with more than 61,000 people, they did not clearly lower infection rates.

“Probiotics prevent colds.”

Probiotics do not reliably prevent colds: in trials, somewhat fewer people taking them got colds, but the evidence is weak and the true benefit is likely…

“Carrageenan nasal sprays prevent colds.”

Carrageenan nasal sprays have not been shown to prevent colds: the only trial testing this found no clear drop in cold symptoms.

“Homeopathic cold remedies work.”

Homeopathic cold remedies have not been shown to work: well-run trials found they do no better than a placebo for preventing or treating colds.