Every year in the United States, there are more than 1 billion upper respiratory tract infections and colds. In addition, 5 to 25 percent of Americans get the flu, which results in 200,000 hospitalizations and anywhere from 20,000 to 36,000 deaths, depending on the year. The vast majority of over-the-counter conventional and alternative products have no adequate clinical evidence that they can prevent or treat colds and the flu. That’s why I like to say, “Treat a cold and it will only last 7 days, but if you do not treat it, well then you might be sorry because it can last up to a week.”
While there are a few supplements that have clinical data suggesting they can prevent or treat colds and the flu, what you really want to look for is a supplement that might be able to prevent or help treat pneumonia (along with conventional medicine) because that is the real killer. It’s the most common life-threatening complication of the flu, and young children and the elderly are at the highest risk for it.
In the United States, pneumonia is the number one cause of death from an infection and the sixth most common cause of death overall. Therefore, the annual debate about which dietary supplements do and do not prevent colds and the flu is a nonproductive distraction.
Being hospitalized or dying from a cold is unheard of, but dying from the flu is common because it’s easy to develop a deeper lung infection. One last tip: Don’t look for a supplement that “boosts your immune system”; this means nothing, and many companies have gotten in trouble with regulatory agencies over these claims in the past.
What are Common Cold and Flu?
Colds and the flu—considered cytokine diseases—are caused by viruses. When you are otherwise healthy and get sick, your immune system pumps out protein molecules called cytokines, which help battle the virus and lead to many of the symptoms you experience—sneezing, coughing, a runny nose, and puffy eyes.
It’s the body’s immune response to the virus that makes you feel so bad, not the virus itself. In fact, there were so many deaths in the flu pandemic of 1918 (it killed 3 to 5 percent of the global population) because a lot of people had never dealt with such a strong virus and their immune systems overreacted!
That’s why it makes no sense when supplements claim they can “boost” your immune system. It’s already boosted! What you really want is higher-quality immune surveil-lance with a strong memory for any previous infections (imagine a home security system that could track people who have come into your house, recognize them, and then immobilize them if necessary).
Rhinoviruses cause 30 to 80 percent of colds each year, but there are more than 200 other viruses that could be the culprit. Cold viruses take hold and proliferate primarily in the nose (people like me who have big noses can hold a lot of virus!), and they’re passed by touch, like when people wipe their noses and then shake hands or grab a bar on a bus or subway that someone else touches a short time later.
Flu viruses, on the other hand, can enter through the nose, eyes, and mouth. They get passed around when infected folks cough, sneeze, or talk, which transmits small virus-filled water droplets out of their mouths and noses and into yours. You can also come in contact with flu viruses by touching infected surfaces, such as desks and doorknobs. Some flu viruses can live up to 3 days on surfaces!
If you have symptoms that come on gradually and are primarily above the neck—sneezing, sore throat, watery or itchy eyes—you probably have a cold. If you have symptoms that come on quickly, are severe, and are above and below the neck—fever (a key symptom of the flu), shivering, sweating, achy muscles and limbs—you’ve probably caught the flu. I like to say “one is a nuisance and the other is a knockout.” You can differentiate them with testing, but symptoms often overlap.
Home Remedies For Common Cold and Flu
1. Vitamin C 250 to 1,000 milligrams a day for prevention during periods of intense exercise and stress and especially for treatment along with conventional cold and flu medicines
I can hear it already. You’re thinking, I can’t believe Moyad made cheap, old vitamin C number 1! Well, give me a moment to explain. In the 1920s, American physician Alfred Hess discovered that pneumonia was one of the most common causes of death from untreated scurvy. Later he said that a lack of “antiscorbutic factor” (vitamin C or ascorbic acid) can lead to scurvy and increase the risk of lung infections. In 1934, Polish-born biochemist Casimir Funk (what an awesome name for a researcher or musician), who is credited with inventing the name vitamin, noted that an epidemic of pneumonia in Sudan went away when doctors gave vitamin C.
Fast-forward to today, and there is more research suggesting benefits: A meta- analysis of vitamin C research, which was published in the prestigious Cochrane Database of Systematic Reviews, concluded that “overall, the results of the five identified trials suggested vitamin C is beneficial in preventing and treating pneumonia.”
The largest meta-analysis of vitamin C demonstrated that ingesting several hundred milligrams or more per day was associated with a significantly lower risk of pneumonia, and a faster recovery from pneumonia when used with conventional medicine. (Remember, pneumonia is often what kills people who have the flu.) No other dietary supplement has this kind of pneumonia data, which involved school kids, Marine recruits, and the elderly. Vitamin C is also safe to use during pregnancy, and this speaks volumes about its safety for children and adults.
After 30-plus clinical trials involving more than 11,000 individuals, we know that taking 1,000 milligrams a day (2,000 milligrams max) of vitamin C lowers the duration of the common cold in kids and adults by up to 20 percent. Individuals who have an increased risk of temporary immune suppression due to stress, intense exercise (which is a type of stress), or extreme environments may have the most to benefit in terms of vitamin C: Five clinical studies involving approximately 600 soldiers, runners, and skiers under extreme stress (sub-arctic exercise conditions) showed a more than 50 percent reduction in the risk of getting a cold. (If I’m training for a marathon or long race and am putting in ridiculous amounts of exercise over several months, I’ll take 500 to 1,000 milligrams of vitamin C daily.)
Researchers have also found that vitamin C helps reduce common cold–induced asthma. There isn’t much data in the area of flu prevention or treatment, which is true for all dietary supplements, but preliminary investigations suggest vitamin C may help produce certain compounds, like interferon, that can help in the fight against the flu as long as you’re vaccinated.
There has been some concern over the potential for ascorbic acid to increase uri-nary oxalate levels in individuals at risk for kidney stones, but this is mainly after long-term use of high dosages (1,000 or more milligrams daily), and most people need extra vitamin C for only a week or two when they feel like they’re getting a cold or are susceptible to one.
Additionally, in my own research I’ve found that a nonacidic form of vitamin C known as calcium ascorbate (I used Ester-C) has the potential to reduce or have no impact on oxalate levels in individuals without a history of kidney stones. There are only a few very rare circumstances where vitamin C should not be taken, such as with the medical condition hemochromatosis (a genetic defect that leads to too much iron absorption, and vitamin C encourages absorption).
So, how can vitamin C prevent colds in some people, reduce the duration of a cold in others, and help treat pneumonia?
- It may protect against cellular stress caused by infections.
- The concentration of vitamin C in immune cells is much higher than in the
- blood (10 to 50 times higher, on average) and in most organs of the body, which suggests a greater need for vitamin C for immune cells so they can do what they do.
- It may also help certain immune cells mature and release compounds that help kill bacteria and viruses. Some infections actually impact the metabolism of vitamin C, which reduces amounts in the blood, urine, and immune cells.
- Vitamin C is involved in the chemotaxis of monocytes and macrophages, which means it might provide our immune cells with added energy to help them migrate to the source of infection.
- It regenerates the antioxidant form of vitamin E in the body, which may also help with immunity.
- Vitamin C increases levels of a compound called glutathione, which enhances the immune system.
Still, it is incredible to me how some health care professionals dismiss the research related to vitamin C and the common cold (more than 30 good clinical trials have been completed—probably the most for any dietary supplement).
A lot of folks have told me through the years that Emergen-C, Airborne, and other cold formulas really appear to work, and I always point out that they all have one thing in common—they all have about 1,000 milligrams of vitamin C per tablet or packet! You could just take vitamin C. You might ask, why not just eat the recommended five servings of fruits and vegetables a day? Won’t that be enough? No. That will only get you about 200 to 300 milligrams of vitamin C, and only if you’re lucky to consistently pick the few fruits and veggies with the most C (like papaya, strawberries, oranges, and broccoli). Plus, only 10 to 20 percent of the population eats five servings a day!
2. (tie and moving up fast) Pelargonium sidoides 30 (1.5 milliliters) three times a day for 10 days for cold treatment
I’m going to break two rules of not recommending 1) a supplement that requires taking a lot of drops or pills and 2) a homeopathic product. The first is primarily a convenience and compliance issue, and as for the second, since there are still detectable levels of active ingredient in this herbal product, I think Pelargonium sidoides should be considered a dietary supplement (unlike many other homeopathic remedies, which are very diluted).
P. sidoides is a species of South African geranium that’s been used for centuries in Zulu medicine and has two randomized trials showing it can improve symptoms of acute bronchitis (which is usually caused by a virus). Its consistent history of effectiveness for respiratory symptoms and safety in kids and adults is what spurred me to include it in my top three for cold treatment (not for prevention). It appears to work by inducing the interferon system and upregulating cytokines in protecting host cells from viral infection.
This liquid herbal product is easy to find (look for Umcka ColdCare and follow the dosage instructions on the box), and the side effects are similar to a placebo. The primary product used in clinical trials comes from Willmar Schwabe Pharmaceuticals in Germany and is also known as EPs 7630 in many studies. It appears to reduce the duration and severity of common cold symptoms within 5 days, but more commonly 10 days.
It worked better for nasal congestion and drainage, sneezing, sore and scratchy throat, hoarseness, and headache than for fever, cough, and muscle aches. Weakness, exhaustion, and fatigue were also improved. By day 10, about 79 percent versus 31 percent (placebo group) felt better, and it reduced days missed from work by about 1 to 11⁄2. It could be argued that since most positive P. sidoides studies have been funded by the company, we should be skeptical. This is fair, but it does not change the fact that the studies had good methodology, efficacy, and safety.
3. (tie) American ginseng (Panax quinquefolius) 200 milligrams twice a day or Panax ginseng 100 milligrams a day for prevention during cold and flu season
Research has shown that American ginseng can activate some immune cells (macrophages), may increase cytokine and antibody production, and can even help natural killer cells in the body that go after infections. It’s been studied against a placebo in at least five different clinical trials, and it reduced the number of colds by 25 percent (not that impressive, but not that bad) and the duration of colds or acute respiratory infections by as much as 6 days (very impressive). The most common dosage was 200 milligrams twice a day for 8 to 16 weeks (with 4 percent ginsenosides).
In one impressive trial with Panax ginseng (Ginsana), 227 healthy adults who had been vaccinated for the flu took 100 milligrams of a ginseng extract or placebo for 12 weeks. The ginseng group had a 65 percent reduction in colds. Panax ginseng is getting funding for some large future trials, so keep your eye on it. (Preliminary results with larger dosages, up to 3,000 milligrams per day, have shown some benefit for flu prevention.)
Here’s the catch with these products when it comes to colds and flu: While the effective active ingredient in ginseng for improving fatigue is something called ginsenosides, some ginseng products that have shown benefits for colds do not contain them. So there may be other active ingredients responsible for the benefits that researchers aren’t aware of yet. In other words, it’s difficult to say exactly which product is the best to choose, whether it’s a supplement like COLD-FX or Ginsana (Panax ginseng), which contains 4 percent ginsenosides. I don’t endorse one type of ginseng product over another because the research is unclear (they both may work in a similar fashion).
Side effects reported with American ginseng include gastrointestinal upset, headache, anxiety, and insomnia. (The last two are not surprising since it is one of the only dietary supplements proven to reduce fatigue and improve energy levels in some people when taken long term.) So taking it in the late afternoon or evening can increase the odds that you’ll have trouble sleeping. But if you’re sick and need to keep working, ginseng could play a role in reducing the fatigue and weakness associated with colds or the flu.
Never take ginseng if you’re pregnant or breastfeeding because this has not been adequately studied. Similarly, I do not believe kids should take it because it hasn’t been well studied in this population either. Also, there have been some case reports of drug interactions (warfarin, phenelzine, and alcohol), so, as always, check with a pharmacist or doctor you trust before taking this supplement. Overall, side effects generally have been similar to a placebo in trials.
4. (tie) Brewer’s yeast–derived fermentate or beta-glucans from yeast 250 to 500 milligrams a day for prevention and treatment of cold and flu symptoms
Modified yeast products are essentially yeast that has been placed under some sort of laboratory-induced stress to produce more immune-fighting compounds. The product EpiCor has the most human research so far. People who took 500 milligrams per day for 12 weeks had fewer cold and flu symptoms and a shorter duration of symptoms than with a placebo. They also reported less nasal stuffiness, hoarseness, and weakness. (These supplements have also been found to reduce nasal allergy symptoms and improve gut immune antibody levels in separate clinical trials.) Full disclosure: I assisted in the design and research of some of these clinical trials for EpiCor, and our research was given one of the highest awards in the supplement industry. I no longer consult for this company, but I am as convinced of the research today as I was many years ago when these trials were conducted. I am happy with the overall research done on yeast-based products for cold and flu symptoms.
Other components of yeast, such as beta-glucan, have immune surveillance and modifying properties that can increase the strength of the immune response. Yeast-based products, such as EpiCor and Wellmune, are interesting because they contain so many potentially beneficial ingredients that identifying the one that is clearly responsible for a particular outcome is kind of like asking which compound from a multivitamin is the most important.
The safety of these products has been excellent in trials, with side effects similar to or even less than a placebo. There is some concern that people with inflammatory bowel disease should not use yeast products because the immune response they prompt could theoretically cause a flare-up in symptoms, but this is not definitive so talk to your doctor.
People often ask me if just using brewer’s or baker’s yeast has the same impact. It is safe but does not have near the amount of research, so I like to stick with what worked in the clinical trials. I believe modified forms of these yeasts provide enhanced immune benefits beyond what the original forms deliver. It’s certainly safe to experiment and be your own guinea pig.
5. (tie) Zinc (acetate or gluconate) 10 to 15 milligrams every 2 to 3 hours until cold symptoms disappear or 10 to 20 milligrams a day for cold and flu symptoms (only for treatment)
Zinc is an essential mineral that’s used in hundreds of metabolic pathways in the body. There is no doubt that a deficiency of this mineral can increase the risk of infection. Research has shown zinc can block cold viruses from attaching inside the nose and protect cell membranes from toxins produced by these infectious agents. Yet, there is that side effect thing! The reason zinc comes in tied for third place—and at low dosages—is because it is very toxic in large doses. Even when zinc works, many people quit taking it because they feel the benefits do not outweigh the side effects (bad taste and nausea).
One of the largest reviews of past clinical trials of zinc supplements found that they appear to reduce cold symptoms in adults (by 1 to 2 days more than placebo), but not kids, when taken within 24 hours of symptom onset and that zinc acetate impacted symptoms a little more than the gluconate or sulfate forms. Subjects took 10 to 15 milligrams every 2 to 3 hours until symptoms began to disappear. Overall, more than half of these clinical trials showed efficacy. The acetate and gluconate forms have the most research in general, but they’re also less apt to bind to additives in supplements and other products, which could reduce the amount absorbed by the body.
There is some research showing that normalizing zinc levels (because there’s a deficiency) could improve cell-mediated immunity, which is needed when you’re fighting the flu and pneumonia.
Do not take zinc to prevent colds or the flu; only take it when you’re sick. And avoid zinc inhalers and nasal gels; they can reduce your sense of taste or smell, sometimes permanently. Also, take zinc with food to reduce the risk of stomach upset.
Elderberry has shown promise for the treatment of colds and the flu. In two small studies done more than 20 years ago, up to 4 tablespoons of elderberry extract per day for 3 to 5 days along with conventional treatment cleared up flu symptoms faster than a placebo. (Both studies used the “original formula” Sambucol supplement, with 3.8 percent extract.) While I’m a bit skeptical due to the age of the studies, it appears safe, so I cannot reject it as an option unless some study proves that elder-berry extract is clearly ineffective. Throw in a few recent laboratory studies and it still seems that the benefit of these extracts (now there are many) outweighs the risk.
7. Andrographis paniculata
Andrographis paniculata, or Nees extract, is an herbal extract that’s also known as Chiretta, King of Bitters, or Kalmegh, that has been used widely in India (one common brand is Kalmcold). The herb has demonstrated some anti- inflammatory and immune-enhancing benefits, which stem from its potential primary active ingredient known as andrographolide.
It has been studied over and over for the treatment of colds, but researchers still haven’t been able to identify the exact amount needed of the active ingredients. The most common dosage of andrographolide used in most of the clinical trials was 60 milligrams per day for 3 to 7 days. There is no good research on the potential for allergic reactions to this herbal, and the number of reports has been small. In other words, use at your own risk.
8. Vitamin D
Vitamin D might help, but only in cases of extreme deficiency. Let me repeat that: I recommend this for cold and flu prevention and treatment only if your blood test is very low—10 ng/mL or less. If you’re deficient, raising blood levels higher (20 ng/mL) or back to normal (30 ng/mL) could have a large impact on your risk of getting colds and the flu as well as pneumonia and other serious infections, such as tuberculosis. Known as the sunshine vitamin, D activates cathelicidins, a group of natural antimicrobial peptides made by immune cells and other cells in the body. It also stimulates immune cells to protect the body from infections.
If you have normal or near-normal levels, vitamin D won’t help you fight off viruses. The VIDARIS (Vitamin D and Acute Respiratory Infection Study) randomized trial—one of the best and most rigorous ever conducted—looked at whether healthy individuals can benefit from D supplementation.
Participants received 200,000 IU of vitamin D3 (one megadose) at the start of the study, another 200,000 IU dose 1 month later, and 100,000 IU monthly thereafter for a total of 18 months (the recommended daily intake for adults is 600 to 800 IU per day). Compared to a placebo, the D supplementation did not reduce the incidence or severity of an upper respiratory tract infection in healthy adults (332 of them) with near-normal vitamin D levels.
9. Juice concentrate supplements
Juice concentrate supplements, concentrated extracts of fruits and vegetables, can be a convenient way for some people to get their five servings a day. Although these supplements don’t contain fiber, they can be helpful for some people who can’t tolerate the real thing for whatever reason. Recent research shows that people (health care workers) who took these juice concentrate supplements daily saw a potentially significant reduction in cold- symptom days (fewer colds in general and less severe symptoms) over 8 months compared to placebo. This looks interesting, and I’m hoping we see more research in this area.
What Supplements Are Useless For Treating Common Cold and Flu?
This supplement has had some positive research, but it hasn’t been consistent. The biggest problem with echinacea is that it hasn’t done well in more rigorous studies. On top of that, echinacea is a member of the large Asteraceae family (aster, daisy, sunflower), which can cause serious allergic reactions in certain people and may increase the risk of side effects from some drugs. Given the lack of research and the potential side effects, the risk is higher than the benefit to me.
There are no well-done clinical trials that show these supplements aid in the prevention or treatment of colds or the flu. Malodorous belching is the biggest problem with these supplements.
They’re being promoted for everything these days, but the research is weak in this area right now. When experts boast that taking probiotics in food or supplements may reduce antibiotic use, well that’s groovy, but you don’t need antibiotics for the majority of cold and flu cases because they’re caused by viruses, not bacteria.
Reviews of more than 50 other products showed that there isn’t enough data out there to support any other supplements for colds and the flu beyond what is recommended in this section. There is a ton of competition, but you have to look at what has been tested the most; what has the most consistent impact against colds, the flu, and pneumonia; and what is safe enough to use for kids, cost effective, and easy to find.
What Supplements Are Suitable For Kids to Treat Common Cold and Flu?
Vitamin C (250 to 500 milligrams per day) is safe and may shorten the duration of a cold in kids. (You can also pair it with conventional flu remedies for the flu.) In one of the only recent reviews of past clinical trials with children, researchers found that zinc could reduce the risk of pneumonia, with more of a potential impact on severe pneumonia. Yet the good studies have come from India, Bangladesh, Peru, and South Africa, where there may be large zinc deficiencies, and critics suggest these results would not be the same if the studies had been done in the United States. I believe zinc supplementation is controversial for kids, and I would never recommend a child take more than 10 milligrams a day of elemental zinc from gluconate, sulfate, or acetate for several days. And since there’s such a high risk for nausea and bad taste, giving your kids zinc supplements isn’t really worth it anyway.
What Lifestyle Changes Can Help With Common Cold and Flu?
Heart healthy = immune healthy
You saw this one coming, right? People are always asking me how they can improve their immune health. Anything that is heart healthy also promotes normal immune function and can reduce the risk of illness. Factors associated with a lower risk of heart disease (low cholesterol; normal blood pressure, blood sugar, and weight; and no tobacco) are all associated with lower rates of illness, including hospitalization from the flu. Exercise in moderation (30 to 45 minutes daily) also improves immune function, and so does adequate sleep. Gee, what a shocker! Even a heart-healthy diet (which is low in calories and high in fiber, omega-3s, fruits, and especially vegetables and incorporates healthy fats) is the best diet for the immune system.
Irrigating the back of the throat, where bacteria and viruses can set up shop, can significantly reduce the risk of infection. Gargle with several ounces of water several times a day. Using warm salt water can soothe a sore throat because the salt draws out excess water in throat tissues, reduces inflammation, and clears mucus and other irritants from the back of the throat.
Wash your hands regularly
Antibacterial soaps are a waste of money because they haven’t been shown to work better than regular soap and they promote resistance. Wash your hands with regular soap and water, making sure you clean the front and back of your hands and your fingernails each time. Follow this up with a 62 percent (or more) ethyl alcohol hand sanitizer gel.
Flush your nose
Use a metered saline nose spray in each nostril several times a day to loosen potential bacteria and viruses; it can also get rid of allergens that are stuck in there.
Research actually shows that upbeat, positive people are less likely to develop a cold, and when they do get sick, they’re more likely to report milder symptoms (happy person = happy immune system).
Significant stress and crowds can increase the risk of colds. This is the reason why researchers love to conduct their cold and flu studies in military boot camps, schools, and office environments.
Lose (or clean) your tie
Preliminary research suggests that health care professionals infrequently wash their neckties, which are reservoirs of pathogenic microorganisms. Want to do your family and friends a favor? Skip the tie during cold and flu season. Next comes the stethoscope, another hotbed of bugs.
What Else to Know About Common Cold and Flu?
An antihistamine, like the kind you use for allergies, can help tame sneezing, a runny nose, and watery eyes, and combining it with a decongestant will reduce symptoms even more. However, antihistamines do not work better than a placebo for a cough.
If you think you’ve caught the flu, get to your doctor within the first 48 hours of having symptoms and see if you qualify for Tamiflu. A recent review of the research, published in the journal BMJ, showed concerning side effects, such as nausea, vomiting, and headaches, and potentially less efficacy against the flu compared to previous reviews. Talk to your doctor about this latest controversy.