Help Patients Avoid Mishaps With Cold and Flu Supplements

Winter will bring questions about "natural" cold and flu remedies.

Most of these supplements lack good evidence. But many patients think they help...and may want to give them a try.

In general, steer patients toward other strategies to prevent or treat colds and flu...vaccination, handwashing, saline nasal sprays, etc.

But if they want a supplement, help ensure choices aren't harmful.

Echinacea. Explain Echinacea purpurea is the most broadly studied species for colds...but results overall are mixed.

Tell patients with ragweed allergies not to use echinacea, since it's closely related to ragweed...and caution that echinacea can cause an allergic skin rash in some children.

Elderberry. Point out that many products don't have the 22 g/day dose studied for flu. Plus elderberry should be started within 48 hours of flu symptoms for any possible benefit...and it's dosed QID.

Explain safety data are lacking for elderberry in kids under 12.

Honey. Suggest 0.5 to 2 teaspoons at bedtime as an alternative to OTC cough suppressants for kids. It may also be worth a try in adults.

But avoid honey in kids under 1 year due to botulism risk.

Tell patients there's no evidence that "raw" or "dark" forms...or products with honey (Stodal Honey, etc)...work better than plain honey.

Vitamin C. If patients ask, inform them that most studies use 1 to 3 g/day...but even these high doses may have no effect on colds.

Plus warn that these doses may increase risk of diarrhea and kidney stones and should be avoided in kids.

Zinc. Explain that zinc lozenges need to be started within 24 to 48 hours of cold symptoms...and used about every 2 hours while awake, until symptoms resolve.

Caution that lozenges may cause a bad taste or nausea...and that zinc may decrease absorption of some antibiotics (quinolones, etc).

Ginseng. Cold-FX contains an extract of North American ginseng. Tell patients there's no proof Cold-FX Extra Strength 300 mg BID is more effective than regular-strength 200 mg BID. And advise patients on warfarin to avoid it, since the INR can be decreased.

Combo products (Airborne, Emergen-C, etc) aren't likely to add benefit. Check individual ingredients for interactions or "red flags."

Use our chart, Supplements for Colds and Flu in Adults, for nuances to consider...and our Natural Medicines to screen for interactions.

Key References

  • www.naturalmedicines.com (12-17-19)
  • J Evid Based Complementary Altern Med 2017;22(1):166-74
  • Cochrane Database Syst Rev 2018;(4):CD007094
Pharmacist's Letter Canada. January 2020, No. 360102



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