The Encyclopedia of Natural Medicine, 3rd Ed.

Common Cold


• Nasal discomfort with watery discharge and sneezing

• Dry, sore throat

• Red, swollen nasal passages

• Swollen lymph nodes on the neck

The common cold can be caused by a wide variety of viruses that are capable of infecting the upper respiratory tract—the nasal passages, sinuses, and throat. We are all constantly exposed to many of these viruses, yet the majority of us experience the discomfort of a cold only once or twice a year. This situation implies that a decrease in resistance or immune function is the major factor in catching a cold.

In general, the individual with a cold will experience a general malaise, fever, headache, and upper respiratory tract congestion. Initially there is usually a watery nasal discharge with sneezing followed by thicker secretions containing mucus, white blood cells, and dead organisms. The throat may be red, sore, and quite dry.

Usually a cold can be distinguished from other conditions with similar symptoms (influenza and allergies for example) by some common sense. Influenza is much more severe and usually occurs in epidemics. Allergies may be an underlying factor in decreasing resistance and allowing a virus to infect the upper airways, but usually allergies can be differentiated from the common cold by the fact that no fever occurs with allergies, there is usually a history of seasonal allergic episodes, and there is no evidence of infection.

Therapeutic Considerations

Maintaining a healthy immune system is the primary way of protecting against an excessive number of colds. If you catch more than one or two colds a year, you may have a weak immune system. To strengthen the immune system, follow the recommendations in the chapter “Immune System Support.”

What to Do Once You Catch a Cold

Once a cold develops, there are several things that can speed up recovery. It should be noted, however, that in people with a healthy, functioning immune system, a cold should not last more than three or four days. Even if you utilize a wide variety of natural healing methods, once a cold is well under way it is very difficult to completely throw it off in two days. Do not expect immediate relief in most instances when using natural substances. In fact, since most natural therapies for colds involve assisting the body rather than suppressing symptoms, as drugs do, often the symptoms of the cold temporarily worsen.

Many of the symptoms of a cold are a result of our body’s defense mechanisms. For example, the potent immune-stimulating compound interferon, released by our blood cells and other tissues during infections, is responsible for many flu-like symptoms. Another example is the fever. While an elevated body temperature can be uncomfortable, suppression of fever is thought to counteract a major defense mechanism and prolong the infection. In general, fever should not be suppressed during an infection unless it is dangerously high (>104°F).


The immune system functions better when the parasympathetic nervous system (a part of our autonomic nervous system) assumes control over bodily functions, as happens during periods of rest, relaxation, visualization, meditation, and sleep. During the deepest levels of sleep, potent immune-enhancing compounds are released and many immune functions are greatly increased. The value of sleep and rest during a cold cannot be overemphasized.


Drink lots of fluids, particularly water and unsweetened herbal teas. Increased fluid consumption offers several benefits. When the membranes that line the respiratory tract get dehydrated, they provide a much more hospitable environment for cold viruses. Drinking plenty of liquids and using a vaporizer help maintains a moist respiratory tract, which repels viral infection. Drinking plenty of liquids will also improve the function of white blood cells by decreasing the concentration of solutes in the blood.

It should be noted that the type of liquids you drink is very important. Studies have shown that consuming concentrated sources of sugars such as glucose, fructose, sucrose, honey, or orange juice greatly reduces the ability of white blood cells to kill bacteria.13 If you want to drink fruit juices, dilute them with water. Drinking concentrated orange juice or other sweet juice during a cold probably does more harm than good.

Avoid Sugar

As mentioned above, sugar, even if derived from natural sources such as fruit juices and honey, can impair immune function.13 This impairment appears to be due to the fact that glucose (blood sugar) and vitamin C compete for transport sites into the white blood cells. Excessive sugar consumption may decrease vitamin C levels and result in a significant reduction in white blood cell function.

Vitamin C

Many claims have been made about the role of vitamin C (ascorbic acid) in the prevention and treatment of the common cold. It has been more than 40 years since Linus Pauling wrote the book Vitamin C and the Common Cold.4Pauling based his opinion on several studies showing that vitamin C was very effective in reducing the severity of symptoms as well as the duration of the common cold. This makes sense, as vitamin C is not only critical for immune system function but also directly antiviral. There have now been more than 30 clinical trials involving 11,350 study participants that have been designed to judge the effectiveness of vitamin C in the prevention or treatment of the common cold. A very detailed analysis of these studies has concluded that vitamin C can be quite beneficial in reducing the risk of developing a cold in high-stress situations, and it may also reduce the duration of a cold by a day or so. In six trials involving a total of 642 marathon runners, skiers, and soldiers on subarctic exercises, the risk of developing a cold was reduced by 50% in the vitamin C group compared with a placebo group. While vitamin C can reduce the duration of a cold slightly, it does not seem to have any effect on reducing symptoms.5

Zinc Lozenges

One of the most popular natural approaches to the common cold is the use of zinc lozenges. There are good scientific data to support this practice, as several studies have now shown that zinc lozenges provide relief of a sore throat due to the common cold. Zinc is a critical nutrient for optimal immune system function and, like vitamin C, also exerts direct antiviral activity.6

Thirteen placebo-controlled comparisons have examined the therapeutic effect of zinc lozenges on the common cold. Three trials used zinc acetate in daily doses of over 75 mg, with pooled results indicating a 42% reduction in the duration of colds. Five trials used zinc salts other than acetate in daily doses of over 75 mg, with a 20% reduction in the duration of colds. Five of the trials used a total daily zinc dose of less than 75 mg and uniformly found no effect.7

Good results were seen in one study with zinc gluconate; it may have been due to the formulation of the lozenge. In the study, 100 patients experiencing early signs of the common cold were provided a lozenge that contained either 13.3 mg zinc (from zinc gluconate) or a placebo.8 They took the lozenges as long as they had symptoms. The subjects kept track of symptoms such as cough, headache, hoarseness, muscle ache, nasal drainage, nasal congestion, scratchy throat, sore throat, sneezing, and fever. The time to complete resolution of symptoms was significantly shorter in the zinc group than in the placebo group. Complete recovery was achieved in 4.4 days with zinc compared with 7.6 days for the placebo. The zinc group also had significantly fewer days with coughing (2.0 days compared with 4.5 days), headache (2.0 days vs. 3.0 days), hoarseness (2.0 days vs. 3.0 days), nasal congestion (4.0 days vs. 6.0 days), nasal drainage (4.0 days vs. 7.0 days), and sore throat (1.0 day vs. 3.0 days).

The formulation in this study differed from those in the studies that did not show much benefit from zinc lozenges; the lack of benefit in the latter group of studies may have been due to an ineffective lozenge formulation. The explanation for this can be found in an interesting study that evaluated the actual amount of ionized zinc released into the saliva by various lozenges. It appears that in order for zinc to be effective it must be ionized in saliva. The study showed that sucking on hard candy lozenges containing zinc gluconate and citric acid delivered an insignificant amount of ionized zinc.9 It was found that saliva completely suppresses the ionization of zinc in the presence of citric acid. Certain sweetening agents such as mannitol and sorbitol also prevent the ionization of zinc. The best zinc lozenges are those that provide zinc acetate or gluconate and do not contain citric acid, mannitol, or sorbitol. They may be sweetened with the amino acid glycine. In contrast to citric acid, mannitol, or sorbitol, glycine—even in excessively large amounts—was found not to interfere with ionization of zinc. In fact, 90% of the zinc was ionized in this study.

So what does all this mean? In order for a zinc lozenge to be effective, it must be free from sorbitol, mannitol, and citric acid. Use lozenges supplying 15 to 25 mg elemental zinc. Dissolve in the mouth every two waking hours after an initial double dose. Continue for up to seven days.


There have been more than 300 scientific investigations on the immune-enhancing effects of echinacea—one of the most popular herbs in the treatment of the common cold. Mixed results from clinical studies with echinacea are most likely due to lack of or insufficient quantity of active compounds. The effectiveness of any herbal product depends on its ability to deliver an effective dosage of active compounds. If the product had sufficient levels of active compounds, it would be effective. If not, it would probably be no more effective than a placebo. For example, in one double-blind study 160 subjects were given either echinacea or a placebo and then exposed to a common cold virus. Infection occurred in 44 and 57% of the echinacea- and placebo-treated subjects, respectively, and illness occurred in 36 and 43%. However, the preparation lacked the active components of echinacea—it contained no echinacosides or alkamides and only 0.16% cichoric acid.10

In contrast, a clinical trial using a well-defined echinacea extract containing alkamides, cichoric acid, and polysaccharides at concentrations of 0.25, 2.5, and 25 mg/ml, respectively, prepared from freshly harvested E. purpureaplants (commercially available as Echinilin or Echinamide), showed excellent results.11 In this randomized, double-blind, placebo-controlled trial, 282 subjects 18 to 65 years old with a history of two or more colds in the previous year, but otherwise in good health, were randomly assigned to receive either echinacea extract or a placebo. They were instructed to start the echinacea or placebo at the onset of the first symptom related to a cold, consuming 10 doses the first day and 4 doses per day on subsequent days for seven days. Severity of symptoms was recorded each day, and a nurse examined the subjects on the mornings of days three and eight. A total of 128 subjects contracted a common cold (59 echinacea, 69 placebo). The total daily symptom scores were found to be 23.1% lower in the echinacea group than in the placebo group. Throughout the treatment period, the response rate to treatments was greater in the echinacea group.

Again, to highlight the issue of quality control and source of preparation, several studies with less well-defined echinacea products showed little benefit, especially in experimentally induced rhinovirus infections.12 For example, in one double-blind study, 302 volunteers from four military institutions and one industrial plant in Germany were given either a placebo or alcohol-based tinctures from either E. purpurea or E. angustifolia dried root for 12 weeks. The main outcome measure was time until the first upper respiratory tract infection. The secondary outcome measures were the number of participants with at least one infection, global assessment, and adverse effects. The time until occurrence of the first upper respiratory tract infection was 66 days in the E. angustifolia group, 69 days in the E. purpurea group, and 65 days in the placebo group. In the placebo group 36.7% had an infection, while in the E. angustifolia group the proportion was 32% and in the E. purpurea group it was 29.3%. These results indicate that there was no significant benefit with either form of echinacea, although there was an approximately 20% reduced risk of infection in the echinacea groups.

In one of the most detailed clinical trials, 719 patients were assigned to one of four groups: no pills, placebo pills (blinded), echinacea pills (blinded), or echinacea pills (unblinded). Echinacea groups received 8 tablets on the first day and 4 tables on the subsequent four days. Each tablet contained the equivalent of 675 mg alcoholic extract of dried Echinacea purpurea root and 600 mg alcoholic extract of Echinacea angustifolia root; the placebo group received the same number of tablets. The results showed only a statistically insignificant trend in reduction of the cold duration (half a day) and a reduction of severity of approximately 10%.13

The result from this trial indicates that a major issue with some of the echinacea research may be the echinacea preparations used—weak ethanol-based tinctures derived from dried root. Clinical studies of upper respiratory tract infections treated with extracts of fresh Echinacea purpurea whole plant or aerial plant, especially in liquid form, are consistently positive compared with those using dried echinacea extracts or powdered herbs, especially in solid forms (tablets or capsules). It is possible that echinacea may exert direct local effects and that contact with lymphatic tissue in the mouth and throat is extremely important in an upper respiratory tract infection. Reasonably large and well-designed, double-blind, placebo-controlled studies have found that preparations of echinacea from the aerial portion of the plant produce modest effects in staving off colds as well as reducing symptoms and duration.12,14

Another study showed good results when 108 patients with initial symptoms suggesting a cold received an extract of the freshly pressed juice of E. purpurea (EchinaGuard) at a dosage of 4 ml twice per day or a placebo for eight weeks.15 In the echinacea group, 35.2% of patients remained healthy, compared with 25.9% in the placebo group. The length of time between infections was 40 days with echinacea, 25 days with the placebo. When infections did occur in patients receiving echinacea, they were less severe and resolved more quickly. Patients showing evidence of a weakened immune system (CD4:CD8 ratio <1.5) benefited the most from echinacea.

The results from another trial were especially encouraging, as they suggested that echinacea can not only make colds shorter and less severe but also sometimes stop a cold that is just starting.16 In this study, 120 people were given a preparation from the freshly pressed juice of E. purpurea or a placebo as soon as they started showing signs of getting a cold. Participants took either echinacea or the placebo at a dosage of 20 drops every two hours the first day, then 20 drops three times a day for nine more days. Fewer people in the echinacea group felt that their initial symptoms actually developed into “real” colds (40% of those taking echinacea vs. 60% taking the placebo). Also, among those who did come down with real colds, improvement in the symptoms started sooner in the echinacea group (after four days instead of eight days). Both results were statistically significant. However, echinacea’s ability to shorten the duration of colds was more dramatic.

Not all studies using the freshly pressed juice of E. purpurea or EchinaGuard have shown positive effects in reducing duration of upper respiratory infections, severity, or both. For example, a study of children 2 to 11 years old was particularly disappointing, as the results indicated not only that it was ineffective but also that its use was associated with an increased risk of rash.17 In another double-blind trial, 128 patients received 100 mg freeze-dried pressed juice from the aerial portion of E. purpurea or a placebo three times per day until cold symptoms were relieved or until the end of 14 days, whichever came first.18 No statistically significant difference was observed between treatment groups for either total symptom scores or mean individual symptom scores. The time to resolution of symptoms was also not statistically different. The failure in this trial may have been due to the above-mentioned lack of direct contact with the oral cavity’s lymphatic system.

Clearly, more research using well-characterized echinacea preparations at appropriate dosages in well-designed trials is necessary. Currently, the gold standard for evaluating cold remedies involves inoculating healthy individuals with rhinovirus. Though the concentration of viral assault is much greater than what one might encounter in the real world, any substance showing efficacy in this model is regarded as being highly efficacious. In one study, 48 healthy adults received the freshly pressed juice of E. purpurea (EchinaGuard) or a placebo, 2.5 ml three times a day, for seven days before and seven days after intranasal inoculation with rhinovirus (RV-39).19 A total of 92% of echinacea recipients and 95% of placebo recipients were infected. Colds developed in 58% of echinacea recipients compared with 82% of placebo recipients. Although administration of echinacea before and after exposure to rhinovirus did not decrease the rate of infection, it did appear to reduce the clinical development of a cold. However, because of the small sample size, it was not possible to detect statistically significant differences in the frequency and severity of illness.

South African Geranium (Pelargonium sidoides)

The common name for this plant, Umckaloaba, is a close approximation of the word in the Zulu language that means “severe cough” and is a testimony to its effect in bronchitis (see the chapter “Bronchitis and Pneumonia”). In addition to showing significant benefits in bronchitis and sinusitis, it has also shown benefit in treating the common cold. In one study, 103 adult patients were randomly assigned to receive either 30 drops (1.5 ml) of an extract of P. sidoides (EPs 7630 or Umcka) or a placebo three times a day. From baseline to day five, symptom intensity improved by 14.6 points in the EPs 7630 group compared with 7.6 points in the placebo group. After 10 days, 78.8% of those in the EPs 7630 group vs. 31.4% in the placebo group were clinically cured. The mean duration of inability to work was significantly lower in the EPs 7630 treatment group (6.9 days) than in the placebo group (8.2 days). EPs 7630 significantly reduces the severity of symptoms and shortens the duration of the common cold by a little more than a day compared with a placebo.20



• Many of the symptoms of a cold are a result of our body’s defense mechanisms.

• With a healthy, functioning immune system, a cold should not last more than three or four days.

• The value of sleep and rest during a cold cannot be overemphasized.

• Consuming plenty of liquids and using a vaporizer will maintain a moist respiratory tract that helps repels viral infection.

• Vitamin C can help prevent the common cold and can also help reduce the duration by about one full day.

• Zinc lozenges can be effective in reducing the duration of symptoms if they are properly prepared and taken in dosages of 75 mg per day.

• Mixed results from clinical studies with echinacea are most likely due to insufficient quantity of active compounds.

• Clinical trials of an extract from freshly harvested E. purpurea plants have shown excellent results.

• In addition to showing significant benefits in bronchitis and sinusitis, an extract of Pelargonium sidoides has also shown benefit in treating the common cold.



Although the focus of this chapter was on the use of natural methods to assist the body in recovering from the common cold, prevention is by far the best medicine. The old adage “An ounce of prevention is worth a pound of cure” is true for the common cold as well as the majority of other conditions afflicting human health. For more information on supporting the immune system, see the chapter “Immune System Support.”

General Recommendations

• Rest (bed rest is best).

• Drink large amount of fluids (preferably diluted vegetable juices, soups, and herb teas).

• Limit simple sugar consumption (including fruit sugars) to less than 50 g a day.

Nutritional Supplements

• Vitamin C: 500 to 1,000 mg every two hours (decrease if it produces excessive gas or diarrhea) along with 1,000 mg mixed bioflavonoids per day

• Zinc lozenges: The best lozenges are those that utilize glycine as the sweetener. Those that use citric acid, mannitol, or sorbitol should be avoided. Use lozenges supplying 15 to 25 mg elemental zinc. Dissolve in the mouth every two waking hours after an initial double dose. Continue for up to seven days. Prolonged supplementation (more than one week) at this dose is not recommended, as it may lead to suppression of the immune system.

Botanical Medicines

• Take one of the following:

  images Echinacea (first two forms are preferred):

  – Fluid extract of the fresh aerial portion of E. purpurea (1:1): 2 to 4 ml (1/2 to 1 tsp) three times a day (preferred)

  – Juice of aerial portion of E. purpurea stabilized in 22% ethanol: 2 to 4 ml (1/2 to 1 tsp) three times a day (preferred)

  – Dried root (or as tea): 1 to 2 g three times a day

  – Freeze-dried plant: 325 to 650 mg three times a day

  – Tincture (1:5): 2 to 4 ml (1/2 to 1 tsp) three times a day

  – Fluid extract (1:1): 2 to 4 ml (1/2 to 1 tsp) three times a day

  – Solid (dry powdered) extract (6.5:1 or 3.5% echinacosides): 150 to 300 mg three times a day

  images Pelargonium sidoides (EPs 7630 or equivalent preparation):

  – Adults: 1.5 ml three times per day or 20 mg tablets three times per day for up to 14 days

  – Children: age 7–12 years, 20 drops (1 ml) three times per day; under age 6, 10 drops (0.5 ml) three times per day