There is evidence that certain supplements can reduce the chance of getting a cold and/or reduce the severity of a cold.

Zinc can directly kill cold viruses and, when taken as a lozenge (as opposed to a pill), it may significantly reduce the duration and severity of cold symptoms. However, it needs to be taken properly and at the correct dosage and it should not be taken for more than about a week due to concerns about excessive zinc.

In healthy adults, a certain combination of probiotics taken for 3 months was found to reduce the risk of catching a cold by about 12% compared to placebo. The probiotics also reduced the number of days of symptoms among those who did catch a cold.

Unless you are deficient in vitamin C, there's not much evidence that it can help prevent a cold. However, if taken routinely during cold season, it may reduce the severity of a cold.

Evidence for echinacea has been mixed. In general, this herb may be more effective for reducing the risk of catching a cold, rather than reducing symptoms of an existing cold. One large study found that taking a branded liquid echinacea three times daily during cold season modestly reduced the risk of getting a cold; if taken 5 times daily during a cold, it reduced the amount of pain medication, such as aspirin, used during colds.

Andrographis (Andrographis paniculata), sometimes referred to as "Indian echinacea," is an herb which has been shown in several clinical studies to help prevent colds and reduce cold symptoms such as earache, sleeplessness, nasal drainage, and sore throat. Much of the research on this herb has been conducted on a branded formula (Kan Jang from Swedish Herbal Institute) which contains a combination of andrographis and Siberian ginseng. Although generally considered to be safe and well-tolerated, it should be noted this herb may not be suitable for people with certain autoimmune diseases or gallbladder disease.

Vitamin D supplements may help reduce the occurrence of colds and upper respiratory infections, but only in people who do not already have sufficient blood levels of vitamin D (20 ng/mL). In these people, moderate daily doses may be more effective than extremely large, periodic doses.

For pregnant and nursing women, getting 400 mg of DHA from fish or fish oil supplements has been shown to reduce colds in their infants, but only for infants of women with otherwise low intake of DHA.

Preliminary studies of American ginseng extracts suggest that it might help prevent colds, but there isn't enough good evidence to support this use. Other studies have shown that Asian ginseng may boost the immune system, but the evidence is mixed on whether or not this leads to fewer colds.

Preliminary evidence suggest that beta glucan (a type of soluble fiber from sources such as yeast or grains) may improve certain measures of immune system function — although the evidence is mixed as to whether or not this translates into a reduced risk of a cold. For example, a study in otherwise healthy adults who had recurring colds found that 900 mg of beta glucan (Yestimun, Leiber GmbH, Germany) taken daily for 4 months reduced the number of colds by 25% compared to placebo (Auinger, Eur J Nutr 2013), and a daily dose of either 250 mg or 500 mg of another beta glucan product (Wellmune WGP) was found to reduce the incidence of respiratory infections in runners when taken for one month following a marathon (Talbott, J Sports Sci and Med 2009). However, another study found 500 mg of Wellmune WGP did not decrease the incidence of respiratory infections in adults compared to placebo (Feldman, J Appl Res 2009).

There is some evidence that a branded fermented yeast product containing beta glucan (EpiCor, Embria Health Sciences) may modestly help to increase certain measures of immune function and reduce the occurrence of colds.

NAC (N-acetyl-cysteine) has been shown to thin mucus but there is little evidence that oral supplements help with colds. Oral NAC, however, may decrease the frequency of chronic bronchitis.

There is some evidence that regular use of garlic may help prevent colds. One study found that taking a garlic supplement daily throughout the winter reduced the likelihood of catching a cold by almost two-thirds, and those who caught a cold recovered about one day faster than those who did not take garlic (Josling, Adv Ther 2001).

Glutathione is an antioxidant produced in the liver which is important for immune function. It is sometimes promoted to boost the immune system or help to ward off colds. To date, one small study found that a dose of 250 mg or 1,000 mg per day for six months reduced oxidative stress compared to placebo - although there does not appear to be any evidence that it prevents colds or reduces cold symptoms.

Some people have reported taking melatonin to help boost the immune system and promote sleep while having a cold. Very preliminary evidence suggests melatonin has some antiviral properties (Vielma, Acta Trop 2014), although there does not appear to be any research specifically on colds in people.

Bromelain has been reported to reduce nasal inflammation and improve breathing difficulty in people with sinusitis. ('s Review of Digestive Enzyme Supplements includes products containing bromelain).

Several clinical studies suggest elderberry extract may help reduce and shorten the duration of symptoms of colds and flu. However, most of these studies are small and company-funded, so more research is needed. Much of the research to-date has used a particular elderberry extract, Sambucol. None have shown elderberry to prevent colds or flu. Although rare, be aware that a case of acute pancreatitis was reported in 2019 in a 51-year-old man after he took two to three doses of elderberry extract (Sambucol). He reported having similar symptoms (abdominal pain, nausea, and vomiting) years prior after taking one dose of the same extract. His condition improved after treatment with steroids (Weissman, Dig Dis Sci 2019).

Astragalus is often promoted to help fight colds when taken at the onset of a cold. Preliminary evidence suggests it may help to stimulate the immune system, although there do not appear to be studies in people on the effects of astragalus on cold symptoms.

Olive leaf extract is promoted to boost the immune system and fight colds. One study in high school athletes found that taking olive leaf extract did not prevent colds, but it reduced the duration of illness that occurred by about 28% (Somerville, Nutrients 2019).

Although some people have reported preventing colds with Oscillococcinum, a homeopathic treatment, there is little evidence for this use. Some studies have found a benefit for treating flu, although the evidence for this is also weak. There are many other homeopathic remedies proposed for preventing or treating colds, although, again, there is little quality evidence to support these remedies.

There is no evidence that honey can prevent or shorten colds, but it may relieve symptoms better than some over-the-counter medicines. An analysis of data from 14 clinical trials found that honey improved overall symptoms and reduced the frequency and severity of cough compared to usual care. In particular, honey reduced cough frequency better than the antihistamine diphenhydramine (ex: Benadryl) and comparable to the cough suppressant dextromethorphan (Ex: Robitussin). Most of the reviewed studies gave honey in doses of 0.5 to 2 teaspoons per day to children and about 1 tablespoon per day to adults, often at bedtime, but it remains uncertain if these doses are optimal. Most of the studies included in the analysis used pure honey, but some combined honey with other ingredients such as milk or coffee (Abuelgasim, BMJ Evid Based Med 2020). While there is interest in manuka honey for health purposes, none of the studies included in the analysis used manuka honey. (Note: Be aware that infants younger than 12 months should not consume honey of any kind due to the risk of infant botulism. Topical administration is also inadvisable for infants.)

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January 5, 2016

My readings show that beta glucan (1,3 and 1,6) has properties that helps with many infections. I have found it useful. Also looked at any possible negative effects of beta gluten and found none. I would love to have CL comment.
January 21, 2016

Hi Vinod - We've now added information about beta glucan to the answer above.

January 4, 2016

Please address the use of mushrooms for their ability to boost immunity, like Reishi mushrooms and the others included in supplements such as Host Defense by MyCommunity. They have outstanding reviews on Amazon, and when I had a review of SpectraCell Lab results, I was told I should take Host Defense to boost my immunity.
February 18, 2016

Hi Steve - We've added a CL Answer about reishi mushroom supplements here:

January 3, 2016

I have not seen any comments about EPICOR ~ the supplement derived from yeast ~ which my family and I have taken daily during the winter months for a few years to prevent colds ~ it works !!
January 21, 2016

Hi Kate - We've now added a CL Answer about EpiCor here:

December 2, 2017

Larger, INDEPENDENT studies are needed to confirm these benefits as well as the long-term safety of Epicor.

So I will not buy now 2017.12

James D16271
December 10, 2017

I have had dramatic result using Epicor. Whereas before using I had several colds a year I have had none since I started using it about five years ago. The same has been true for other members of my family.

February 21, 2019

A new product from contains Epicor: Life Extension Florassist Nasal. It is expensive, but the main reason for high cost is probably the other ingredient it contains: Lactobacillus acidophilus L-92.
Epicor is from USA and L-92 is from Japan. L-92 is probably expensive even if you travel to Japan and buy it there.

Jenny 18572
October 27, 2019

I had a worsening of MS after taking Epicor. A naturopath wasn’t convinced it was caused by Epicor and recommended I try it again. I did, and again had a worsening of MS. So, it certainly seemed to boost my immune system. Caveat emptor if one has autoimmune illnesses worsened by such an effect, or a genetic tendency towards.

Stephanie 7988
October 4, 2015

I have been using ELDERBERRY STANDARIZED for decades. In Germany it is taken throughout flu season. Echinacea when taken over 10 days lowers immune system. Too much zinc has toxic effects. STANDARDIZED ELDERBERRY, has been my go to for decades. When I fly I take one prior to flying and then another after landing. Now, I no longer get airplane flus or colds. Just be sure it is standardized otherwise who knows what you are getting. Haven't had the flu in years. No flu vaccine for me. If you do get sick take Elderberry ASAP and your flu or cold days and severity will be greatly reduced.
Good life and good health to all.

October 19, 2019

Looks like there are many research articles on the efficacy of elderberry. Hope Consumer Labs will give us an idea on which ones are best as far as having good manufacturing practices and price.
October 24, 2019

Hi Marcia -- We will be testing elderberry supplements this year, so be sure to check your newsletter, where the results will be announced when the results are published.

October 1, 2015

My son had purchased a zinc solution for use in detecting zinc deficiency. Feeling a cold coming on and being aware of Zicam, a zinc nasal spray product for dealing with colds, I decided to try snorting some of the solution up each nostril. I feel this worked in one application to knock out the cold virus. I have used it two or three times now. I believe Zicam is no longer sold in this country as there were reports that it permanently damaged the sense of smell in some users. The zinc solution I have is zinc sulfate heptahydrate in purified water, whereas Zicam contains zinc acetate and zinc gluconate and other things.
October 1, 2015

Hi Robert - Based on the concerns with zinc given nasally, this approach seems risky. In addition, zinc's benefits have only been shown when used every few hours, not as a single application.

September 28, 2015

Umcka Original Drops work great for me. It is best to start before the cold symptoms really take hold. If my throat gets scratchy or sore, or I'm sneezing more than I should... you know that time in process when you naively hope it won't get worse but then it does. Start then.

I will also start it when I know I've been exposed, such as when my partner has gotten sick, or when I've been in a car with someone in the contagious phase. Then I don't get sick at all.

It seems to keep the symptoms from getting worse while my immune system knocks out the virus. I take it up to 5 times a day for a few days, then taper off over a couple of weeks. I've avoided having a full blown cold for years now.

They also have a Cold & Flu version, but I haven't tested that.

October 2, 2015

Agreed! I have been using it for over 10 years and always have a bottle on hand! It almost always works to prevent, unless the cold has gotten too far along. And I have suggested this product to several friends and family, whoever has tried it, has found it to work as well. It's a Swedish herbal, I get the "original" drops, add it to a bit of water. It has a pleasant, light taste. I understand it boosts the immune system temporarily. Not useful over an extended period.

December 3, 2017

I use the syrup and day/night powder at the first sign of cold and it seems to lessen severity and shorten duration. I like that it has quite a bit of research showing efficacy.

December 3, 2017

I too am a big fan of UMCKA. the active ingredient Pelargonium is an African herb used for bronchitis. But UMCKA ColdCare knocks out my cold fast. I use the extra relief mint-menthol formula.

December 11, 2017

I've been using Umcka for 10 years and have told dozens of people about it. I understand that it as approved by the German Commission E, for what that is worth.

I also rely on Quercetin which usually comes with Bromelain.

September 28, 2015

There are two protocols I have used over the past 5 years to prevent colds and nip them in the bud when the symptoms first surface. Before i disclose the protocols let me add that prior to 5 years ago a routinely had 4-6 upper respiratory events a year with a severe episode of bronchitis once ever 2-3 years. The first protocol is started at the first signs of a viral infection. It involves following the anti-viral program spelled out in the Life extension website at The ingredients include supplements having antiviral properties. These include pure garlic, Cimetidine (from Tagamet), DHEA, Lactoferrin, Zinc Loenges, Aged Garlic Extract (Kyolic brand) and Melatonin. For the last two years I have not used this protocol as I have had no serious cold symptoms. Two years ago I started taking Glutathione (GSH), the Setria formulation, 1000 mg/day. The friend who put me onto GSH claims to have not had a serious cold in 15 years.

September 28, 2015

At the first sign of a cold, andrographis capsules, 3 x day for a few days and the cold does not develop and symptoms are gone.

September 27, 2015

Does the herb "andrographis" have an effect on colds?

September 27, 2015

Try cold fx it really helps! Personal experience.

Carol 7974
September 27, 2015

I find the combination of Yin Chiao and Oscillococcinum to be infallible. HOWEVER the Oscillo is only effective if taken at that first moment when you think you "might" be getting a cold. Take it then follow with Yin Chiao for three days, whether or not you feel better, which you most likely will. I also use zinc lozenges. Remember with the Oscillo to follow the instructions for all homeopathic remedies -- no peppermint, alcohol, coffee, clean mouth, etc.

September 27, 2015

Can any of this be generalized to influenza? If not, could you do a follow-up article about supplements and the flu?
September 28, 2015

Thank you for your question, James. Please see our separate CL Answer about supplements for flu:

February 27, 2019

Beta glucan in some studies is maybe the ultimate immune system support item. I have had no major sickness other than digestive issues in 3 years of using it. I don't get flu shots anymore. I visit a old person's retirement home environment a couple of times a week and work in a construction type environment in and outside, sometimes eat with dirty hands. I am in no means saying Beta Glucan can upset my stomach. Bad food does that.

September 2, 2020

I read yesterday that Dr. Fauci and others are skeptical of claims that a supplement could help boost the immune system because1) most people’s immune systems probably don’t need to be boosted and 2) sending it into overdrive could be dangerous. I suppose they mean a cytokine storm? which I've read (sorry, I can't remember where) could be one explanation for COVID. I'd be very interested to hear your views!

December 10, 2017

My go to for signs of a cold is Grapefruit Seed Extract. IMHO, Taken 3 times a day at first sign and until symptoms decline has kept my 80 year old body and my college going granddaughter cold free for the 2 years I have known about it.

December 3, 2017

To defeat a cold I use a product called Viragon from Baseline Nutritionals. It has never failed me when taken at the very first symptom - even when I'm not sure it's a symptom yet. Doesn't do a thing if taken too late.

The downsides are 1) it's not cheap and 2) it tastes awful. Well it would - it contains things like horseradish. Well worth it though, in my opinion.

I have no financial interest in this or a competing product.

December 3, 2017

Missing from this list is elderberry extract. Taken at the first minor sign of a cold it can prevent the cold. Taken after it starts it can reduce the length and severity. This is from my own experience, that of the person who recommended it, and the experience of every person to whom I have recommended it.
December 19, 2017

Hi Linda - Thank you for sharing your experience with this. We've added information about elderberry extract in the answer above.

Julie Ann18574
October 27, 2019

I stopped taking the flu shot, tired of spending every winter and some summers with the flu even after 2 flu shots and started taking Nature's Way Elderberry every day for the past 27 years. I had read about it in a medical journal. I have not had the flu in 27 years.

December 3, 2017

I have had extraordinarily good experience over many many years using tincture (liquid pure) Echinacea for preventing colds from settling in and taking over. My fave brand is Herb Pharm (usually Super Echinacea), but I have used others. This my experience, and also works for my husband. This works best when 1. I catch it early, at first notice of symptoms like scratchy throat, a wet-ish sneeze, a bit of a drip, and 2. I use 2 or 3 full droppers-full (depending on how incipient and strong the symptoms) in a little water up to several times a day for up to a couple of days. Often symptoms retreat within a day.

December 3, 2017

While there is "little quality evidence to support these remedies" [homeopathic remedies, that is], there is now clear evidence that homeopathic preparations are no better than placebo.

October 28, 2019

Even if homeopathic is "only" the placebo effect (it isn't because it works on animals too) the "placebo effect" is actually powerful medicine. It's just not medicine you can make money off of so Capitalists try and deny it. All healers worldwide, except Western medicine, understand that we are energetic beings and we are affected by things that influence our energy. Google "energy medicine the scientific basis" if you want to see the science.
October 28, 2019

It is true that placebos can appear to have an effect. However, it is the role of good clinical trials to identify remedies that do more than a placebo -- which is what we look for at ConsumerLab when we evaluate the literature around a product. Of course, something that has a real effect typically has side-effects, about which we also report, and these need to be weighed against the possible benefits.

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