Zinc Supplement Review

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  Evaluated for:
Effectiveness Rating Effectiveness Rating
Relief of the common cold
+1 (Slight Evidence)


  • Zinc is thought to prevent and treat the common cold. Unfortunately, it’s unclear whether or not this is true. Approximately half of the 100 studies we reviewed showed a decrease in the severity and duration of cold symptoms, and half did not.
  • Zinc has a broad range of safety and a low risk of side effects. Zinc toxicity is highly unlikely unless you take a very high dose for a very long time.
  • Although the evidence is mixed, it might be worth having it on hand and using with the onset of cold symptoms. It might help as much as chicken soup.


  • If it works, and it’s not clear if it does, zinc should be started with the very first cold symptoms. So in order to start it the very moment you need it, that means you’ll need to keep a supply at the ready throughout the entire cold season.
  • Only half the people who took zinc reported improvements in their cold symptoms. This may be due to the type of zinc they took, although that isn’t clear. Zinc gluconate and zinc acetate may be more effective than zinc glycinate and zinc citrate.
  • Side effects may include nausea, vomiting, and/or diarrhea. The lozenges may cause an unpleasant taste sensation. Zinc may also interfere with absorption of certain antibiotics called quinolones and tetracyclines, and may cause loss of smell.

Nasal administration of zinc-containing preparations has been linked to permanent, irreversible loss of smell (anosmia). Doses greater than 100 mg per day may be associated with decreased HDL (good) cholesterol, decreased immune function and prostate cancer. These should be discussed with your health care provider.

DOSAGE:If you decide to try it, follow the dosage directions on the package.

CONCLUSION:There is not enough evidence to support the use of zinc for treating the common cold. There are still significant questions about its overall effectiveness, the differences between various kinds of zinc formulations, and the long-term safety of the nasal sprays (see advisory). If you decide to try it, remember to include it in your list of medications when you visit your doctor and other health care providers.

“Zinc.” ConsumerLab.com. ConsumerLab.com LLC, 2013. 8 May 2013.
“Zinc.” Natural Standard –The Authority on Integrative Medicine. Natural Standard, 2013.
“Zinc.” Natural Medicines Comprehensive Database. Therapeutic Research Faculty, 2013. 8 November 2013.
Prasad, A. et al. Duration and Severity of Symptoms and Levels of Plasma Interleukin-1 Receptor, and Adhesion Molecules in Patients with Common Cold Treated with Zinc Acetate. JID (2008) 197:795-802
Plum, L. et al. The Essential Toxin: Impact of Zinc on Human Health. International Journal of Environmental Research and Public Health (2010) 7, 1342-1365
Caruso, T. et al. Treatment of Naturally Acquired Common Colds with Zinc: A Structured Review. CID (2007) 45:569-574
Briefel, R. et al. Zinc Intake of the U.S. Population: Findings from the Third National Health and Nutrition Examination Survey, 1988-1994. The Journal of Nutrition (2000) 130, 1367S-1373S

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