The best option is to avoid getting a cold altogether, but if you do catch one, the next best thing is to get over it fast. The mineral zinc, which is an essential trace element, may help you do just that.
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"There are some evidence-based studies that suggest zinc supplements could be helpful in fighting a cold," says Harry Oken, MD, an internist and member of the medical advisory board for Persona Nutrition.
It's all a matter of timing: Take zinc supplements within the first day of a cold — that is, within 24 hours of when your symptoms first appear — and it may reduce both how long the cold lasts and how bad the symptoms are overall, according to a November 2011 meta-analysis of 13 randomized trials in The Journal of Family Practice.
But why would popping zinc shorten your cold and ease your symptoms? The mineral may help stop the virus responsible for colds — the rhinovirus — from getting comfortable and multiplying in your upper respiratory system, per the Mayo Clinic.
How Much Zinc to Take for a Cold
Taking zinc lozenges can help you recover from a cold three times faster than you normally would, per an April 2017 meta-analysis published in Open Forum Infectious Diseases.
"If my patient gets a cold and they want to add more zinc, I recommend they take zinc in lozenge form (10 to 20 milligrams) for three to seven days," Dr. Oken says.
Zinc RDAs and Upper Limit
The recommended daily allowance (RDA) for zinc is 11 milligrams for adult men and 8 milligrams for adult women, per the National Institutes of Health (NIH). The RDA for pregnant or breastfeeding people increases to 11 and 12 milligrams, respectively.
The upper limit for zinc is 40 milligrams for adults.
Note that in the meta-analysis, it was a dosage of 80 to 92 milligrams per day that led to faster recovery from a cold — this is significantly above the recommended upper limit. The meta-analysis notes that more research is needed to establish the most effective zinc dosage.
Even though zinc may help reduce symptoms and duration of a cold, this is one supplement you don't want to overdo. "You must be very careful when adding zinc in supplement form to ensure you're not getting too much," Dr. Oken says.
Take too much zinc, and you'll prevent the absorption of copper, another essential element, according to the National Academies of Sciences, Medicine and Engineering. Plus, too much zinc can cause gastrointestinal issues, Dr. Oken says. The taste of zinc supplements can be metallic and unpleasant, and it can lead to nausea, per Harvard T.H. Chan School of Public Health.
However, the Open Forum Infectious Diseases meta-analysis does note that taking 80 to 92 milligrams per day for a maximum of two weeks is highly unlikely to lead to any long-term adverse effects.
Zinc Lozenges or Nasal Spay — Which Do You Choose?
Sucking on a zinc lozenge increases the level of zinc in the upper respiratory tract's mucous membranes — that's the spot where the rhinovirus lurks when you have a cold, Dr. Oken says.
A zinc syrup can also lead to the same effect of having the zinc linger in the throat, where the rhinovirus lives, per the Mayo Clinic.
Make sure to stay away from zinc nasal sprays and nasal gels — there have been reports of people losing their sense of smell and taste due to these, according to the NIH.
You'll also want to avoid zinc supplements that include citric acid, which can interfere with the absorption of zinc, according to the Open Forum Infectious Diseases meta-analysis. Vitamin C, or ascorbic acid, is fine, per a 2012 study in the Journal of International Medical Research.
Taking vitamins and cold medications together can be tricky, so check with your health care provider if you are on medications.
"Zinc can bind with the drug in the stomach and form complexes, making it more difficult for the body to absorb the medication," Dr. Oken says. Interactions can occur with thyroid medications as well as certain antibiotics, he notes.
"With zinc-containing supplements, it is important to separate the time you take the supplement from the time you take the medications by 2 to 4 hours to avoid this interaction," Dr. Oken says.
The Best Zinc Supplements to Buy
If you're looking for a zinc supplement to buy before your next cold, here are some recommended options from ConsumerLab.
Remember, with lozenges, you’ll want to let the lozenge dissolve (and not chew it) for the best results.
- The Journal of Family Practice: "Zinc for the Common Cold—Not If, But When"
- Mayo Clinic: "Zinc for Colds: The Final Word?"
- National Institutes of Health: "Zinc Fact Sheet for Health Professionals"
- Harvard T.H. Chan School of Public Health: "Zinc"
- National Academies of Sciences, Medicine and Engineering: "Fruits and Vegetables Yield Less Vitamin A Than Previously Thought; Upper Limit Set for Daily Intake of Vitamin A and Nine Other Nutrients"
- Open Forum Infectious Diseases: "Zinc Acetate Lozenges May Improve the Recovery Rate of Common Cold Patients: An Individual Patient Data Meta-Analysis"
- U.S. National Library of Medicine: "Drug Label Information: Cold-Eeze Zinc Gluconate Lozenge"
- Mayo Clinic: "Cold remedies: What Works, What Doesn't, What Can't Hurt"
- Journal of International Medical Research: " A combination of high-dose vitamin C plus zinc for the common cold"
- NIH: "Zinc"