Colds and Flus

A cold is a respiratory infection caused by one of hundreds of possible viruses. However, because these viruses are so widespread, it is perhaps more accurate to say that colds are caused by a decrease in immunity that allows one of these viruses to take hold.

Colds occur more frequently in winter, but no one knows exactly why. Nearly everyone catches colds occasionally, but some people catch colds quite frequently, and others tend to stay sick an unusually long time.

Conventional medicine can neither cure nor prevent the common cold. Furthermore, none of the over-the-counter treatments have been found to shorten the duration of a cold or even provide significant temporary relief. Some of the natural treatments described in this section may be able to do better.

People often want to take antibiotics for colds, and many physicians will prescribe them—even though antibiotics have no effect on viruses. Many believe that when the mucus turns yellow, it means that a bacterial infection has occurred for which antibiotic treatment is indicated. However, viruses can also produce yellow mucus; and even if bacteria have made a home in the excess mucus, they may be only innocent bystanders and produce no symptoms.

Colds, however, can be complicated by bacterial infections. In such cases antibiotic treatment may be indicated. Decongestants and other symptomatic treatments have not been shown to be dramatically effective.

Principal Proposed Treatments for Colds and Flus:

Remember the old saying "a cold lasts seven days, but if you treat it properly you will get over it in a week"? Actually, it may be possible to prove folk wisdom wrong by using the right natural supplement. The mineral zinc, taken as a nasal spray, can dramatically shorten the duration of a cold. Zinc lozenges may help too. In addition, a significant body of research suggests that the herb echinacea can also significantly shorten colds as well as make them less severe. The herb andrographis also seems to help. Vitamin C might also provide some benefit if used properly. .

In addition to treating colds, there are three treatments that might help prevent colds: andrographis, ginseng and garlic.

Zinc: Appears Effective For Treating Colds If You Use the Right Form

One famous alternative treatment for colds is the use of zinc in nasal spray or lozenges. A recent study found that zinc nasal spray can reduce the duration of your cold by almost 75%. This is a dramatic improvement, so dramatic that it almost qualifies as a cure for the common cold! Zinc lozenges also appear to help, but not quite so powerfully.

When you take zinc this way, you are not using it as a nutrient. Rather, proper forms of zinc release ions that directly inhibit viruses in the nose and throat.

Taking zinc orally as a nutrient might also be useful in some cases. The immune system does not function properly if you dont have enough zinc in your body. Because zinc is commonly deficient in the diet, especially among senior citizens, nutritional zinc supplementation may certainly be useful for those who get sick easily. Indeed, a recent 2-year double-blind study suggests that zinc and selenium taken together in nutritional doses can reduce the number of infections in nursing home residents. Ten other studies performed in third world countries have found that zinc supplements at nutritional doses can increase resistance to infection. However, more isnt better; once you do have enough zinc, getting extra wont help, and might even hurt.

What Is the Scientific Evidence for Zinc Nasal Spray and Lozenges?

In a double-blind, placebo-controlled trial, 213 individuals with a newly starting cold used one squirt of zinc gluconate gel or placebo gel in each nostril every 4 hours while awake. The results were dramatic: Treated participants stayed sick an average of 2.3 days, while those receiving placebo were sick for an average of 9 days, a whopping 75% reduction in the duration of symptoms.

A more recent study found no benefits with zinc nasal spray. In this double-blind, placebo-controlled trial, 185 individuals who had just started to develop cold symptoms were given either a zinc spray or placebo. No benefits were seen in the treated group as compared to the placebo group. However, this study used a much lower amount of zinc per squirt of spray than was used in the study mentioned previously: 50 times lower, to be exact. In addition, the spray contained zinc sulfate rather than zinc gluconate. The exact chemical form of zinc appears to markedly influence its ability to kill cold viruses.

Zinc lozenges also appear to be helpful. For example, in a double-blind trial, 100 people who were experiencing the early symptoms of a cold were given a lozenge that either contained 13.3 mg of zinc from zinc gluconate or was just a placebo. Participants took the lozenges several times daily until their cold symptoms subsided. The results were impressive. Coughing disappeared within 2.2 days in the treated group versus 4 days in the placebo group. Sore throat disappeared after 1 day versus 3 days in the placebo group, nasal drainage in 4 days (versus 7 days), and headache in 2 days (versus 3 days).

Positive results have also been seen in double-blind studies of zinc acetate.

Not all studies have shown such positive results. However, the overall results appear to be favorable. It has been suggested that the exact formulation of the zinc lozenge plays a significant role. Flavoring agents, such as citric acid and tartaric acid, appear to prevent zinc from inhibiting viruses, and chemical forms of zinc other than zinc gluconate or zinc acetate may not work. Sweeteners such as sorbitol, sucrose, dextrose, and mannitol are fine, but the information on glycine as a flavoring agent is equivocal.

For more information, including dosage and safety issues, see the full zinc article.

Echinacea: Reduces Cold and Flu Symptoms and Helps Recovery

Until the 1930s, echinacea was the number one cold and flu remedy in the United States. It lost its popularity with the arrival of sulfa antibiotics. Ironically, sulfa antibiotics are as ineffective against colds as any other antibiotic, while echinacea does seem to be at least somewhat helpful. In Germany, echinacea remains the main remedy for minor respiratory infections.

Echinacea is thought to work by temporarily stimulating the immune system, although this has not been proven. There is no evidence that echinacea strengthens or "nourishes" the immune system when taken over the long term.

There are three main species of echinacea: Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida. E. purpurea is the most widely used, but the other two are also available. It isnt clear if any one type is better than the others.

What Is the Scientific Evidence for Echinacea?

Reducing the Symptoms and Duration of Colds: Double-blind, placebo-controlled studies enrolling a total of more than 800 individuals have found that various forms and species of echinacea can reduce cold symptoms, and help you get over a cold faster. The best evidence regards products made from the above-ground portions of E. purpurea.

For example, in one double-blind placebo-controlled trial, 80 individuals with early cold symptoms were given either E. purpurea extract or placebo. The results showed that individuals who were given echinacea recovered significantly more quickly: just 6 days in the echinacea group versus 9 days in the placebo group.

Another double-blind placebo-controlled trial looked at reduction of the severity of cold symptoms. The results in 246 participants showed that treatment with E. purpurea significantly improved cold symptoms such as runny nose, sore throat, sneezing, and fatigue.

"Aborting" a Cold: A double-blind study suggests that echinacea can not only make colds shorter and less severe, it might also be able to stop a cold that is just starting. In this study, 120 people were given E. purpurea or a placebo as soon as they started showing signs of getting a cold.

Participants took either echinacea or placebo at a dosage of 20 drops every 2 hours for 1 day, then 20 drops 3 times a day for a total of up to 10 days of treatment. The results were promising. Fewer people in the echinacea group felt that their initial symptoms actually developed into "real" colds (40% of those taking echinacea versus 60% taking the placebo actually became ill). Also, among those who did come down with "real" colds, improvement in the symptoms started sooner in the echinacea group (4 days instead of 8 days). Both of these results were statistically significant.

Preventing Colds: Several studies have attempted to discover whether the daily use of echinacea can prevent colds from even starting, but the results have not been promising.

In one double-blind placebo-controlled trial, 302 healthy volunteers were given an alcohol tincture containing either E. purpurea root, E. angustifolia root, or placebo for 12 weeks. The results showed that E. purpurea was associated with perhaps a 20% decrease in the number of people who got sick, and E. angustifolia with a 10% decrease. However, the difference was not statistically significant. This means that the benefit, if any, was so small that it could have been due to chance alone.

Another double-blind placebo-controlled study enrolled 109 individuals with a history of four or more colds during the previous year, and gave them either E. purpurea juice or placebo for a period of 8 weeks. No benefits were seen in the frequency, duration, or severity of colds. (Note: this paper is actually a more detailed look at a 1992 study widely misreported as providing evidence of benefit.)

Similar results were seen in three other studies as well, enrolling a total of over 300 individuals. Another study often cited as evidence that echinacea can prevent colds actually found no benefit in the 609 participants taken a whole. Only by looking at subgroups of participants (a statistically questionable procedure) could researchers find any evidence of benefit, and it was still slight.

For more information, including dosage and safety issues, see the full echinacea article.

Andrographis: May Both Prevent and Treat Colds

Andrographis is a shrub found throughout India and other Asian countries, sometimes called "Indian echinacea" because it is believed to provide much the same benefits. It has been used historically in epidemics, including the Indian flu epidemic in 1919, during which andrographis was credited with stopping the spread of the disease. Recently, it has become popular in Scandinavia as a treatment for colds.

Although we dont know how andrographis might work for colds, some evidence suggests that it might stimulate immunity. Interestingly, the ingredient of andrographis used for standardization purposes, andrographolide, does not appear to affect the immune system as much as the whole plant extract.

What Is the Scientific Evidence for Andrographis?

According to a few well-designed studies, andrographis can reduce the symptoms of colds and possibly prevent colds as well.

Reducing Cold Symptoms: Three double-blind placebo-controlled studies enrolling a total of about 250 participants have found that andrographis significantly reduces the duration and severity of cold symptoms.

For example, a 4-day double-blind placebo-controlled trial of 158 adults with colds found that treatment with andrographis significantly reduced cold symptoms. Participants were given either placebo or 1,200 mg daily of an andrographis extract standardized to contain 5% andrographolide. The results showed that by day 2 of treatment, and even more by day 4, individuals given the actual treatment experienced significant improvements in symptoms as compared to participants in the placebo group. The greatest response was seen in earache, sleeplessness, nasal drainage, and sore throat, but other cold symptoms improved as well.

Similar benefits were seen in two double-blind placebo-controlled studies of an herbal combination treatment containing both andrographis and Eleutherococcus, enrolling a total of over 200 individuals.

Another double-blind study, which involved 152 adults, compared the effectiveness of andrographis (at either 3 g per day or 6 g per day) versus acetaminophen for sore throat and fever. The higher dose of andrographis (6 g) decreased symptoms of fever and throat pain, as did acetaminophen, while the lower dose of andrographis (3 g) did not. There were no significant side effects in either group.

Preventing Colds: According to one double-blind, placebo-controlled study, andrographis may increase resistance to colds. A total of 107 students, all 18 years old, participated in this 3-month trial that used a dried extract of andrographis. Fifty-four of the participants took two 100-mg tablets standardized to 5.6% andrographolide daily—considerably less than the 1,200 to 6,000 mg per day that has been used in studies on treatment of colds. The other 53 students were given placebo tablets with a coating identical to the treatment. Then, once a week throughout the study, a clinician evaluated all the participants for cold symptoms.

By the end of the trial, only 16 people in the group using andrographis had experienced colds, compared to 33 of the placebo-group participants. This difference was statistically significant, indicating that andrographis reduces the risk of catching a cold by a factor of two as compared to placebo.

For more information, including dosage and safety issues, see the full andrographis article.

Vitamin C: May Be Modestly Helpful for Treating Colds; Not So Helpful for Prevention

As the most famous of all natural treatments for colds, vitamin C has been subjected to irresponsible hype from both proponents and opponents. Enthusiasts claim that if you take vitamin C daily, you will never get sick, while critics of the treatment insist that vitamin C has no benefit at all.

However, a cool-headed evaluation of the research indicates something in between. Numerous studies have found that vitamin C supplements taken at a dose of 1,000 mg daily or more can modestly reduce symptoms of colds and help you get over a cold faster.

This evidence regards daily use of vitamin C throughout the cold season. Many people use vitamin C for colds in a different way: they only begin taking it when cold symptoms start. Relatively few studies have evaluated this approach.

A large, double-blind, placebo controlled trial was recently conducted to determine whether vitamin C helps when taken only at the onset of a cold. This double-blind trial enrolled 400 individuals with new-onset cold symptoms. Participants were divided into four different daily vitamin C dosage groups: 30 mg daily (a dose lower than the minimum daily requirement, and used by the researchers as a placebo), 1000 mg, 3000 mg, or 3000 mg with bioflavanoids. Participants were instructed to take the vitamin at the onset of symptoms and for the following two days.

The results showed no difference in the duration or severity of cold symptoms between the groups. High-dose vitamin C, in other words, didnt work.

There are two main possible explanations for these negative results. One possibility is that taking high dose vitamin C at the onset of a cold is not as effective as taking it continuously. Another possibility is that taking vitamin C at the onset of a cold could work, but that two days of treatment simply isnt long enough. (It is actually a bit surprising that researchers used such a short treatment schedule.)

In general, vitamin C has failed to prove effective for preventing colds. However, there are two cases in which vitamin C may help prevent a cold. One is the "post-marathon sniffle." Heavy endurance exercise temporarily weakens the immune system, leading to a high incidence of infection following marathons and triathlons. There is some evidence that vitamin C can prevent such colds. The other situation in which vitamin C might help prevent colds is among individuals who are actually deficientin the vitamin. In such cases, increasing intake of vitamin C might help improve resistance.

For more information, including dosage and safety issues, see the full vitamin C article.

Ginseng: May Help Prevent Colds

Although most people in the West think of ginseng as a stimulant, in Eastern Europe ginseng is widely believed to improve overall immunity to illness. As we have seen, echinacea does not seem to prevent colds. But it appears that regular use of ginseng may be able to provide this important benefit.

There are actually three different herbs commonly called ginseng: Asian or Korean ginseng (Panax ginseng), American ginseng (Panax quinquefolius), and Siberian "ginseng" (Eleutherococcus senticosus). The latter herb is actually not ginseng at all, but some herbalists believe that it functions identically.

What Is the Scientific Evidence for Ginseng?

A double-blind placebo-controlled study looked at the potential immune-stimulating effects of Panax ginseng. This trial enrolled 227 individuals at three medical offices in Milan, Italy. Half were given ginseng at a dose of 100 mg daily, and the other half took placebo. Four weeks into the study, all participants received influenza vaccine.

The results showed a significant decline in the frequency of colds and flus in the treated group compared to the placebo group (15 versus 42 cases). Also, antibody measurements in response to the vaccination rose higher in the treated group than in the placebo group.

While more research is needed, this study suggests that ginseng may be able to do what echinacea, zinc lozenges, and vitamin C cannot: prevent colds.

For more information, including dosage and safety issues, see the full ginseng article.

Garlic: May Also Help Prevent Colds

The herb garlic has a long history of use for treating or preventing colds. However, up until 2001, there was no scientific evidence that it actually works for this purpose. In fact, many people joked that garlic merely makes you smell so bad people stay away from you, and so you dont catch their cold.

A recent study does provide meaningful evidence that garlic might possess cold-fighting powers. In this 12 week, double-blind, placebo controlled trial, 146 individuals received either placebo or a garlic extract between November and February.

The results showed that participants receiving garlic were almost 2/3rds less likely to catch cold than those receiving placebo. Furthermore, participants who did catch cold recovered about one day faster in the garlic group as compared to the placebo group.

Note: that this study does not indicate that taking garlic will help once you already have a cold.

For more information, including dosage and safety issues, see the full garlic article.

Essential Oil Monoterpenes: May Reduce Symptoms

Eucalyptus is a standard ingredient in cough drops and in oils meant to be added to humidifiers. A standardized combination of three essential oils, including oils derived from eucalyptus, has been tested for its usefulness in respiratory conditions. The studied combination includes cineole from eucalyptus, d-limonene from citrus fruit, and alpha-pinene from pine. Numerous double-blind trials have found them effective for sinus infections, acute and chronic bronchitis, and other respiratory conditions, in both adults and children. These oils are all in a chemical family called monoterpenes.

Dosage

In studies, this essential oil combination was taken at a dose of 300 mg 3 to 4 times daily.

Safety Issues

Other than minor gastrointestinal complaints, no side effects have been reported with this essential oil combination. However, be advised that essential oils can be toxic if taken to excess. Maximum safe doses in young children, women who are pregnant or nursing, and individuals with severe liver or kidney disease have not been established.

Other Proposed Treatments for Colds and Flus:

Use of multivitamin, multimineral supplements, or supplements containing zinc and selenium alone, may help prevent infections in elderly individuals.

A 7-month double-blind placebo-controlled study of 571 children in day-care centers in Finland found that use of milk fortified with the probiotic bacteria Lactobacillus GG modestly reduced the number and severity of respiratory infections.

There is some evidence that vitamin E may improve immune function, but whether this translates into an effect on colds has not been determined.

A product containing elderberry as well as small amounts of echinacea and bee propolis has been widely marketed as a cold and flu remedy. Weak evidence suggests that this mixture may stimulate the immune system and also inhibit viral growth. In a preliminary double-blind study, the combination significantly reduced the recovery time from epidemic influenza.

Based on a small double-blind study, the supplement arginine might also be helpful for preventing colds.

There is some evidence that the supplement glutamine may, like vitamin C, help prevent post-exercise infections. For example, a double-blind placebo-controlled study evaluated the benefits of supplemental glutamine (5 g) taken at the end of exercise in 151 endurance athletes. The result showed a significant decrease in infections among treated athletes. Only 19% of the athletes taking glutamine got sick, as compared to 51% of those on placebo.

The thymus gland plays a role in immunity. A 1-year double-blind placebo-controlled trial of 16 children with frequent respiratory infections found that treatment with thymus extract could reduce the rate of infection. However, a double-blind placebo-controlled trial of 60 athletes failed to find any significant evidence of benefit with thymus extract for preventing post-exercise infections.

There is some evidence that elements in kelp might help to prevent infection with several kinds of viruses, including influenza. However the evidence is very preliminary at this time.

Various herbs are said to work like ginseng and enhance immunity over the long term, including ashwagandha, astragalus, garlic, maitake, reishi, and suma. However, there is as yet no good evidence that they really work.

Several herbs, including ginger, kudzu, osha, and yarrow, are said to help avert colds when taken at the first sign of infection; but again, there is no scientific evidence that they are effective. Other herbs sometimes recommended to reduce cold symptoms include marshmallow, mullein, and peppermint.

Products containing colloidal silver are sometimes used in the belief that they will prevent colds and otherwise strengthen the immune system; however, because they can cause side effects, we recommend that you do not use them.

Some elderly individuals do not respond fully to the influenza vaccine. Preliminary evidence suggests that combined multivitamin/multimineral supplements may improve their response. However, in another trial, a multivitamin tablet without minerals actually worsened participants response to the vaccine.