Sort Out Claims About Supplements for Cold and Cough

As cough and cold season blows in, you’ll need to help patients separate rumor from truth about natural remedies.

Zinc may shorten the duration of cold symptoms. Truth.

Zinc lozenges seem to shorten cold symptom duration in adults by about 3 days...when started within 48 hours of symptom onset.

Check out our podcast, Rumor vs Truth, Watch/Listen now

Explain that most studies use zinc acetate or gluconate lozenges...typically providing 9 to 24 mg of elemental zinc per dose. The studied regimen is typically 1 lozenge every 2 hours while awake.

But point out that zinc doesn’t seem to PREVENT colds in adults...and evidence is mixed about any prevention benefit in kids.

Educate about adverse effects, such as nausea or metallic taste.

And check for interactions...zinc can reduce absorption and levels of many medications, such as certain HIV meds or antibiotics.

For a deeper dive, review the full zinc monograph in NatMed Pro. And guide conversations using our patient handout.

Vitamin C prevents coldsRumor.

It doesn’t seem to PREVENT colds in most patients. But it might have a modest TREATMENT benefit for kids and adults.

Data suggest that high doses of vitamin C...generally 1 g per day or more...might shorten the duration of cold symptoms by up to 1.5 days.

But clarify that this is only if vitamin C is taken regularly...not just at the onset of cold symptoms.

Counsel that these doses may increase risk of kidney stones in susceptible patients, such as those with a history of kidney stones. And point out that GI upset is more common with doses above 2 g per day.

Honey is effective for cough. True, with conditions.

Honey reduces the frequency and severity of nighttime cough...in children 2 years and older with upper respiratory infections.

And honey seems to work about as well as dextromethorphan at usual doses in pediatric studies.

But explain that honey isn’t shown to reduce the duration of cough...and it’s unclear if honey provides a benefit in adults.

Caution parents to avoid raw honey for infants under 12 months old...due to risk of botulism poisoning. Explain that this isn’t a risk for older kids or adults.

Listen to or watch our latest Rumor vs Truth podcast, where our editors stir the pot about natural cold and flu remedies.

Key References

  • TRC Healthcare. Honey. [Natural Medicines website]. November 6, 2025. Available at: https://naturalmedicines.therapeuticresearch.com/Data/ProMonographs/Honey (Accessed November 6, 2025).
  • TRC Healthcare. Vitamin C. [Natural Medicines website]. November 6, 2025. Available at: https://naturalmedicines.therapeuticresearch.com/Data/ProMonographs/Vitamin-C (Accessed November 6, 2025).
  • TRC Healthcare. Zinc. [Natural Medicines website]. November 6, 2025. Available at: https://naturalmedicines.therapeuticresearch.com/Data/ProMonographs/Zinc (Accessed November 6, 2025).
Pharmacist's Letter. December 2025, No. 411201



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