Natural Cold and Flu Remedies

Americans are turning to cold and flu supplements in greater numbers.

Medically Reviewed by David Kiefer, MD on December 29, 2010
9 min read

This year, people in the U.S. will come down with about 50 million cases of flu and about a billion colds. Although the misery of cold and flu season might be inevitable, one thing is changing: where we look for relief.

Research indicates that many of us are turning away from the over-the-counter medicines we grew up with and toward natural cold and flu remedies, like vitamin C, zinc, echinacea, and others.

  • Last year, we spent more than $1.5 billion on supplements to boost immunity and help ward off colds and the flu.
  • The market for these supplements appears to be growing more than twice as fast as the market for over-the-counter cold and flu drugs.

Experts aren't surprised. "From a conventional medical standpoint, there's just not much that's effective for cold and flu," says David C. Leopold, MD, director of integrative medical education at the Scripps Center for Integrative Medicine in San Diego. "People are trying to find something else that will work."

The incentive may be particularly strong now, given recent FDA reports about the ineffectiveness -- and even risks -- of over-the-counter cold and flu treatments in children.

But do alternative treatments offer the relief that pharmaceutical companies can't? There's growing evidence to suggest that some might -- at least to a modest degree. WebMD turned to the experts to get the details.

First things first: cold and flu viruses are not the same thing. Although colds are a drag, flu is much worse.

  • The symptoms of flu are more severe; they include fever and body aches along with congestion.
  • Flu can be dangerous, too; flu kills more than 30,000 people a year.

But because there's some overlap in symptoms, treatments are often lumped together.

How well do natural cold and flu remedies work? Paul M. Coates, PhD, director of the Office of Dietary Supplements at the National Institutes of Health, says that possible benefits appear to be small. But that's a good thing, in a way.

"If a supplement has a big, positive effect, then we worry about an equally powerful negative effect," Coates tells WebMD. Experts agree that popular natural cold and flu remedies seem to be safe for the average person. That's important when dealing with unproven treatments. As long as there's little risk in trying a supplement, the evidence of a benefit doesn't need to be quite so strong.

To help guide you, here's a rundown of the most notable cold and flu supplements, according to the experts. Note that some have been studied with colds and others with flu.

Vitamin C has been long used as a treatment for the common cold, but you might be surprised at how conflicted the evidence is. Although it seems to boost some aspects of the immune system, studies do not show that vitamin C -- at least in doses of 1 gram per day -- helps prevent colds in most people, though it may be helpful in preventing colds in people who are exposed to cold weather or who undergo extreme exercise.

As a treatment, the evidence is somewhat better. Some studies show that vitamin C can reduce the duration of a cold by as much as 24 to 36 hours. However, other studies show that even very high doses -- 3 grams a day -- have no effect.

Keep in mind that the high doses of vitamin C sometimes recommended for cold and flu can upset the stomach and even cause diarrhea in some people. Leopold is particularly wary of using high doses of vitamin C in children.

Once again, the evidence is mixed. Although some studies do not show that echinacea works as a treatment, others show it can reduce the length and severity of colds by 10% to 30%.

Despite the confusion, many experts are fairly sure that echinacea can help treat colds. Leopold points out that some of the conflicting study results may stem from researchers testing different species of echinacea. So far, the best evidence supports taking echinacea purpurea, which may also work better for adults than for children.

Can echinacea also help prevent you from catching cold or flu viruses? Most studies say no.

Echinacea does have some mild risks. If you have allergies to ragweed or certain flowers in the daisy family, don't take echinacea before talking to your doctor. It may also not be safe for people with certain diseases that affect immunity, such as autoimmune conditions like rheumatoid arthritis and lupus, Leopold says.

Zinc lozenges have become a popular treatment for the common cold. Forms of zinc available on the market include zinc acetate, zinc citrate, zinc gluconate, zinc picolinate, and zinc sulfate.

Taking zinc, either as a syrup or lozenge, through the first few days of a cold may shorten the misery of an upper respiratory infection, the latest research shows. The research -- a review of 15 past studies on the subject -- also found that zinc appeared to prevent colds in people who used it over the course of about five months.

Other studies show no benefit, which may be partly due to the different formulations of zinc.

Some experts suggest that zinc should not be taken for long periods of time. If it is, it may induce a copper deficiency in the body.

Can zinc also help prevent colds or the flu? So far, there isn't good evidence to support zinc lozenges for cold or flu prevention.

There's some promising evidence that elderberry might help treat the flu, Leopold says. Elderberry appears to boost the production of some immune cells and may also help block a virus's ability to spread. One study shows that taking 4 tablespoons a day for three days of a specific formulation of elderberry extract -- Sambucol -- appears to shorten the symptoms of flu by 56%. It also seems to reduce some flu symptoms, like fever. However, the study was small and the full implications aren't clear.

Like a number of other supplements, garlic seems to stimulate the immune system. Garlic may also help fight viruses. Also, there is some preliminary evidence that garlic may lower the risk of catching a cold. Garlic works best when consumed raw, either crushed, diced, or minced. Overcooking garlic may destroy important medicinal compounds and the enzymes necessary for it to be effective.

However, more research needs to be done. Note: Garlic may be dangerous in people taking blood thinners.

Although commonly used as a mild stimulant, the different ginseng species may also boost the immune system and help prevent or treat cold and flu. One species, panax ginseng, may also increase the protection offered by the flu vaccine.

Coates singles out a specific blend of North American ginseng sold as Cold fX. Preliminary results suggest that Cold fX, when taken for several months during flu season, seems to lower the risk of contracting either cold or flu. One study looked at Cold fx as a treatment, and found that it reduced the duration and severity of symptoms. "The jury's still out, but the evidence is promising," says Coates.

"Andrographis is called 'Indian echinacea,'" says Evangeline Lausier, MD, assistant clinical professor at Duke Integrative Medicine in Durham, N.C. "It seems to stimulate the immune system." Studies of andrographis show that it appears to improve cold symptoms significantly, at least when started within three days of the onset. There's also some early evidence that it may reduce the chances of catching a cold, at least when taken for several months beforehand. Most studies have used a specific product called Kan Jang, which combines andrographis with Siberian ginseng (eleutherococcus senticosus).

Many alternative medicines packaged for cold and flu are combinations of some of the herbs and vitamins listed above -- typically echinacea, zinc, high doses of vitamin C, and other ingredients. Although there's no particular reason to think that combination cold and flu products are more dangerous, they're much less likely to have been studied than the individual ingredients that they contain. You might be better off choosing the specific supplements in the dosages you want.

These aren't the only supplements sold as natural cold and flu remedies. Others include astragalus, goldenseal, kiwi, boneset, and homeopathic oscillococcinium. However, so far, there's not enough evidence to say whether they help with cold or flu.

Experts say that natural cold and flu remedies seem fairly safe -- at least when taken in normal doses by healthy adults. The fact that you'd probably only use them for a few days when you're sick adds to their safety.

"The risks of potentially toxic effects from herbs are almost always related to long-term use," says Paul R. Thomas, EdD, RD, scientific consultant for the Office of Dietary Supplements at the National Institutes of Health.

There are some exceptions. Talk to your doctor before taking any herb, supplement, or vitamin if:

  • You are pregnant
  • You have a medical condition
  • You take medicines or other supplements, which may interact to cause problems

Make sure you purchase brands of supplements that bear a USP or NF seal on the label. The USP and NF seals indicate the supplements have undergone quality-control testing. can also be consulted to make sure the product is legitimate.

Also, don't rely on supplements when you truly need medical care.

"I think the biggest risk is when the symptoms don't subside but people just keep trying to treat themselves with supplements instead of seeing a doctor," Leopold tells WebMD. Self-treatment is especially risky when it comes to the flu. Influenza can be dangerous, especially to those who are very young, older, or sick.

Are natural cold and flu remedies safe for kids? It's a question many parents are asking, particularly in light of the risks of cold and cough medicines for children.

Leopold believes that using supplements in children can be a reasonable option -- provided you always check with a pediatrician or family doctor first. Keep in mind that most alternative supplements have never been studied in children specifically. So we can't be certain that a treatment that is effective and safe in adults will work the same way in kids.

Always err on the side of caution. "When a child is really sick, you don't want to waste time messing with herbal stuff," says Lausier. "You need to get them to a pediatrician."

Natural remedies for colds and flu go well beyond herbs and supplements. Good lifestyle and hygiene habits are proven to reduce your risk of getting sick.

  • Eat healthy foods. Get regular exercise. Learn to manage stress. Those are among the best natural ways to prevent colds and flu, says Leopold.
  • Cover your mouth when you cough. Make sure to cough into your sleeve instead of your hand, Lausier says. You'll reduce the odds of passing your germs on to someone else.
  • Wash your hands. Washing with soap for the time it takes to sing two rounds of “Happy Birthday” -- or rubbing your hands with an alcohol-based gel with enough gel to rub hands together for 30 seconds -- remains one of the best ways of protecting yourself from cold and flu germs.

Nowadays, an annual flu vaccine is recommended for most children and adults. It's highly effective and contrary to what you may have heard, the flu vaccine cannot give you the flu. It can save you and your family a lot of misery.

Show Sources


Singh, M. Cochrane Database of Systematic Reviews, 2011.
Paul M. Coates, PhD, director, Office of Dietary Supplements, National Institutes of Health, Bethesda, Md.
Evangeline Lausier, MD, assistant clinical professor, Duke Integrative Medicine, Durham, N.C.
David C. Leopold, MD, director of integrative medical education, Scripps Center for Integrative Medicine, San Diego.
Natural Medicines Comprehensive Database web site: "Natural Medicines in the Clinical Management of Cold and Flu."
Natural Standard web site: "Common Cold" and "Influenza."
Nutrition Business Journal.
Paul R. Thomas, EdD, RD, scientific consultant, Office of Dietary Supplements, National Institutes of Health, Bethesda, Md.
WebMD Medical Reference: "Kids Cold Medicines: New Guidelines."
WebMD Feature: "Cough Medicine: Should You or Shouldn't You?"

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