Are Vitamin C and Echinacea Really Curing the Cold?

From the Lecture series: The Skeptic's Guide to Health, Medicine, and the Media

By Roy Benaroch, M.D., Emory University

Many home remedies, vitamins, and herbs are believed to be effective in curing the cold. However, not all studies support all beliefs. Sometimes, they even put a red X over a common belief, proving it wrong or useless. Vitamin C and echinacea survived the studies so far, or are they already crossed out? Let us try and find out.

The picture shows a young woman with a handkerchief.
Vitamin C has always been used for curing the cold, while some studies suggest it might not be as effective as believed. (Image: Estrada Anton/Shutterstock)

The Six S’s

Curing the cold has been an eternal challenge for health scientists so far. There have been many possibly definite cures for the cold, but none proved to be definite. So far, vitamin C and echinacea seem to have a higher level of acceptance, but are they really curing the cold?

Every new claim needs to meet the six S’s to be reliable. The first important S is the source. Next is the strength of the evidence. Both sides of the scale, the advantages and disadvantages of a new therapy, must be presented.

The study must be salient and not just a sales trick. Lastly, it should be sensible and in line with things that are somehow proven to be right. Otherwise, it needs further proof.

This is a transcript from the video series The Skeptic’s Guide to Health, Medicine, and the Media. Watch it now, Wondrium.

Vitamin C with no Limits?

In 2017, Men’s Journal published an article that told people to take as much vitamin C as possible to “Keep Colds Short and Sweet.”  The study was done at the University of Helsinki on people who took six or eight grams of vitamin C a day at the beginning of the cold. Is it trustworthy?

The source article was published in the journal Nutrients, which is trustworthy. However, the second S, strength, is not fully satisfied. Two earlier studies are combined, but the number of participants is not mentioned. There is one placebo control group, compared to which those taking high doses of vitamin C showed a 17-19% reduction in cold duration.

The picture shows lemon and orange fruit, ginger, cinnamon spice, and honey on a wooden board.
Taking vitamin C is said to have benefits for curing the cold, but it should be noted that the limit for vitamin C is 2000 milligram per day. (Image: marilyn barbone/Shutterstock)

Further, the study’s saliency cannot be approved, as the participants are not described. The results can be applicable to everyone if the participants are like everyone, i.e., of different ages, genders, and health conditions. However, the article is not trying to sell, as there is no link to a product or a specific brand.

The next problem is that the suggested dose is way above the 2,000 milligrams per day that the National Institutes of Health advises, to avoid possible nausea, diarrhea, and abdominal pain. Thus, it is not sensible to take such high doses for such short reductions in cold duration.

Learn more about infections in the headlines.


Echinacea is a popular herbal remedy for curing the cold. In 2003, the Seattle Times wrote that it does not cure the cold for children. Firstly, the study specifies the participants and the target group, which is a positive point.

The study involved 407 children, aged 2-11, and divided into two groups: one received echinacea at the onset of the cold, and the other took a placebo. So far, the study is salient for children and has a strong placebo-control factor. The results showed no difference.

However, the advantages are not mentioned in a scientific way, and only two people are quoted that focus on advantages: a representative of the American Botanical Council and someone who works at an Herbal Medicine center. Instead, they could have pointed out the possible problems with the method and the shortcomings of the story itself to make both sides of the scale balanced.

The quotes from the two people can only be interpreted as salesmanship, although they are against the article’s main theme.

Learn more about selling disease.

Bioforce’s Study on Echinacea

In 2016, The Wall Street Journal published the results of a four-month-long study on one specific brand of echinacea, made by the company Bioforce. The study observed two groups, one taking echinacea and one placebo. The first group had 149 colds in the four months, and the other had 188. The article said that the results were not statistically significant, yet, continued to support taking echinacea.

The picture shows tea prepared form  Echinacea purpurea.
Bioforce’s study was to endorse the use of echinacea for curing the cold, while the results were not statistically significant. (Image: Nataliia Kuznetcova/Shutterstock)

Obviously, the published article had contradictions. When the overall result of a study is statistically insignificant, the separate parts of the study cannot be referred to as significant. Further, the study was paid for by the company that produces the brand under study. It seems that the article published in The Wall Street Journal had clear business goals.

Thus, all the percentages and results brought to support the use of echinacea lose validity after reporting that the overall result is statistically insignificant.

Apparently, vitamin C and echinacea are both among the myths that have developed throughout time as scientists were trying to find ways for curing the cold. Of course, high doses of vitamin C showed some benefit, but the possible disadvantages are not worth the risk.

Common Questions about Curing the Cold with Vitamin C and Echinacea

Q: Does vitamin C cure the cold?

Some studies show that very high doses of vitamin C help curing the cold, but there is a limit for taking it.

Q: Is echinacea an effective cold remedy?

Many people think echinacea is good for curing the cold, but studies have proved that it does not really help with the cold.

Q: What dose of vitamin C can be dangerous?

Although some studies claim that curing the cold is much easier with unlimited doses of vitamin C, the National Institutes of Health advises against taking more than 2,000 milligrams of vitamin C a day because of potential negative health effects like nausea, diarrhea, and abdominal pain.

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