A review of 21 controlled trials using 1 to 8 grams of vitamin C per day found that “in each of the twenty-one studies, vitamin C reduced the duration of episodes and the severity of the symptoms of the common cold by an average of 23%.”⁸ The optimum amount of vitamin C to take for cold treatment remains in debate but may be as high as 1 to 3 grams per day, considerably more than the 120 to 200 mg per day that has been suggested as optimal intake for healthy adults. A review of 23 controlled trials found that vitamin C supplementation produces a greater benefit for children than for adults.⁹ The same review found that a daily amount of 2 grams or more was superior to a daily amount of 1 gram at reducing the duration of cold symptoms.

Zinc interferes with viral replication in test tubes, may interfere with the ability of viruses to enter cells of the body, may help immune cells to fight a cold, and may relieve cold symptoms when taken as a supplement.¹⁰ In double-blind trials, zinc lozenges have reduced the duration of colds in adults but have been ineffective in children.^11,12,13,14 Lozenges containing zinc gluconate, zinc gluconate-glycine, and, in most trials, zinc acetate^15,16 have been effective; most other forms of zinc and lozenges flavored with citric acid,¹⁷ tartaric acid, sorbitol, or mannitol have been ineffective.¹⁸ Trials using these other forms of zinc have failed, as have trials that use insufficient amounts of zinc.¹⁹ For the alleviation of cold symptoms, lozenges providing 13 to 25 mg of zinc (as zinc gluconate, zinc gluconate-glycine, or zinc acetate) are used every two hours while awake but only for several days. The best effect is obtained when lozenges are used at the first sign of a cold.

An analysis of the major zinc trials has claimed that evidence for efficacy is “still lacking.”²⁰ However, despite a lack of statistical significance, this compilation of data from six double-blind trials found that people assigned to zinc had a 50% decreased risk of still having symptoms after one week compared with those given placebo. Some trials included in this analysis used formulations containing substances that may inactivate zinc salts. Other reasons for failure to show statistical significance, according to a recent analysis of these studies,¹⁰ may have been small sample size (not enough people) or not enough zinc given. Thus, there are plausible reasons why the authors were unable to show statistical significance, even though positive effects are well supported in most trials using gluconate, gluconate-glycine, or acetate forms of zinc.

In a double-blind study, supplementation with American ginseng significantly reduced by 27% the number of colds that people experienced over a four-month period, compared with a placebo.²¹ The amount used in this study was 400 mg per day of a freeze-dried extract.

Elderberry has shown antiviral activity and thus may be useful for some people with common colds. Elder flowers are a traditional remedy for helping to break fevers and promote sweating during a cold.^22,23 In a double-blind trial, administration of an elderberry extract decreased the number of days with cold symptoms by 52% and decreased average symptom severity by 58%, compared with a placebo, in people travelling on intercontinental flights. The amount used was 600 to 900 mg per day of an extract standardized to contain 22% polyphenols and 15% anthocyanins. Treatment was begun ten days prior to the flight and was continued for four to five days after arrival at the destination.²⁴

In a double-blind trial, participants took one capsule per day of a placebo or a garlic supplement that contained stabilized allicin (the amount of garlic per capsule was not specified) for 12 weeks between November and February. During that time, the garlic group had 63% fewer colds and 70% fewer days ill than did the placebo group.²⁵ In another double-blind study of healthy volunteers, supplementing with 2.6 grams per day of an aged-garlic extract for 90 days decreased by 58% the number of days on which severe cold or influenza symptoms occurred.²⁶

Geranium (Pelargonium sidoides) is an herbal remedy used in Germany, Mexico, Russia, and other countries for the treatment of respiratory tract and ear, nose, and throat infections. In a double-blind study of children with acute tonsillitis/pharyngitis that was not due to a Streptococcal infection, participants given an extract of geranium had significantly more rapid resolution of symptoms, compared with those given a placebo.²⁷ The amount of the geranium extract used in this study was 20 drops three times per day for six days.

In a double-blind study, a proprietary product containing marshmallow root, licorice root, and elm bark (Throat Coat) was effective in providing rapid, temporary relief of sore throat pain in people with acute pharyngitis.³¹ Throat Coat was taken as a tea in the amount of 5 to 8 ounces, 4 to 6 times per day, for two to seven days.

An analysis of the major zinc trials has claimed that evidence for efficacy is “still lacking.”⁴⁸ However, despite a lack of statistical significance, this compilation of data from six double-blind trials found that people assigned to zinc had a 50% decreased risk of still having symptoms after one week compared with those given placebo. Some trials included in this analysis used formulations containing substances that may inactivate zinc salts. Other reasons for failure to show statistical significance, according to a recent analysis of these studies,³⁸ may have been small sample size (not enough people) or not enough zinc given. Thus, there are plausible reasons why the authors were unable to show statistical significance, even though positive effects are well supported in most trials using gluconate, gluconate-glycine, or acetate forms of zinc.

In a double-blind study of children in Turkey, oral zinc supplementation significantly reduced both the incidence (by 29%) and the duration (by 11%) of the common cold. The amount of zinc used in this seven-month study was 15 mg per day for children with an average age of 5.6 years. The amount of supplemental zinc was doubled at the onset of a cold, and this higher amount was continued until symptoms resolved.⁵⁰

Herbal supplements can help strengthen the immune system and fight infections. Adaptogens, which include eleuthero, Asian ginseng, astragalus, and schisandra, are thought to help keep various body systems—including the immune system—functioning optimally. They have not been systematically evaluated as cold remedies. However, one double-blind trial found that people who were given 100 mg of Asian ginseng extract in combination with a flu vaccine experienced a lower frequency of colds and flu compared with people who received only the flu vaccine.⁵⁰

Herbal supplements can help strengthen the immune system and fight infections. Adaptogens, which include eleuthero, Asian ginseng, astragalus, and schisandra, are thought to help keep various body systems—including the immune system—functioning optimally. They have not been systematically evaluated as cold remedies. However, one double-blind trial found that people who were given 100 mg of Asian ginseng extract in combination with a flu vaccine experienced a lower frequency of colds and flu compared with people who received only the flu vaccine.⁵¹

Red raspberry, blackberry, and blueberry leaves contain astringent tannins that are helpful for soothing sore throats.⁵²Sage tea may be gargled to soothe a sore throat. All of these remedies are used traditionally, but they are currently not supported by modern research.

Red raspberry, blackberry, and blueberry leaves contain astringent tannins that are helpful for soothing sore throats.⁵³Sage tea may be gargled to soothe a sore throat. All of these remedies are used traditionally, but they are currently not supported by modern research.

Boneset is an immune stimulant and diaphoretic that helps fight off minor viral infections, such as the common cold. Several double-blind trials have found that echinacea root tinctures in combination with boneset, wild indigo, and homeopathic arnica reduce symptoms of the common cold.⁵⁴ In addition, linden and hyssop may promote a healthy fever and the immune system’s ability to fight infections. Yarrow is another diaphoretic that has been used for relief of sore throats, though it has not yet been researched for this purpose.

Traditional Chinese Medicine practitioners use Chinese artichoke (Stachys sieboldii), a species similar to wood betony (Stachys betonica), for colds and flu.⁵⁵ It is unknown whether wood betony would be useful for people with the common cold.

Eucalyptus oil is often used in a steam inhalation to help clear nasal and sinus congestion. It is said to work similarly to menthol, by acting on receptors in the nasal mucous membranes, leading to a reduction of nasal stuffiness.⁶⁰Peppermint may have a similar action and is a source of small amounts of menthol.

Goldenseal root contains two alkaloids, berberine and canadine, with antimicrobial and mild immune-stimulating effects.⁶¹ However, due to the small amounts of alkaloids occurring in the root, it is unlikely these effects would occur outside the test tube. Goldenseal soothes irritated mucous membranes in the throat,⁶² making it potentially useful for those experiencing a sore throat with their cold. Human research on the effectiveness of goldenseal or other berberine-containing herbs, such as Oregon grape, barberry, or goldthread (Coptis chinensis), for people with colds has not been conducted.

Goldenseal root should only be used for short periods of time. Goldenseal root extract, in capsule or tablet form, is typically taken in amounts of 4 to 6 grams three times per day. Using goldenseal powder as a tea or tincture may soothe a sore throat. Because goldenseal is threatened in the wild due to over-harvesting, substitutes such as Oregon grape should be used whenever possible.

Elderberry has shown antiviral activity and thus may be useful for some people with common colds. Elder flowers are a traditional diaphoretic remedy for helping to break fevers and promote sweating during a cold. Horseradish has antibiotic properties, which may account for its usefulness in easing throat and upper respiratory tract infections. The resin of the herb myrrh has been shown to kill various microbes and to stimulate macrophages (a type of white blood cell). Usnea has a traditional reputation as an antiseptic and is sometimes used for people with common colds.

Goldenseal root contains two alkaloids, berberine and canadine, with antimicrobial and mild immune-stimulating effects.⁶³ However, due to the small amounts of alkaloids occurring in the root, it is unlikely these effects would occur outside the test tube. Goldenseal soothes irritated mucous membranes in the throat,⁶⁴ making it potentially useful for those experiencing a sore throat with their cold. Human research on the effectiveness of goldenseal or other berberine-containing herbs, such as Oregon grape, barberry, or goldthread (Coptis chinensis), for people with colds has not been conducted.

Goldenseal root should only be used for short periods of time. Goldenseal root extract, in capsule or tablet form, is typically taken in amounts of 4 to 6 grams three times per day. Using goldenseal powder as a tea or tincture may soothe a sore throat. Because goldenseal is threatened in the wild due to over-harvesting, substitutes such as Oregon grape should be used whenever possible.

Elderberry has shown antiviral activity and thus may be useful for some people with common colds. Elder flowers are a traditional diaphoretic remedy for helping to break fevers and promote sweating during a cold. Horseradish has antibiotic properties, which may account for its usefulness in easing throat and upper respiratory tract infections. The resin of the herb myrrh has been shown to kill various microbes and to stimulate macrophages (a type of white blood cell). Usnea has a traditional reputation as an antiseptic and is sometimes used for people with common colds.

Elderberry has shown antiviral activity and thus may be useful for some people with common colds. Elder flowers are a traditional diaphoretic remedy for helping to break fevers and promote sweating during a cold. Horseradish has antibiotic properties, which may account for its usefulness in easing throat and upper respiratory tract infections. The resin of the herb myrrh has been shown to kill various microbes and to stimulate macrophages (a type of white blood cell). Usnea has a traditional reputation as an antiseptic and is sometimes used for people with common colds.

Boneset is another immune stimulant and diaphoretic that helps fight off minor viral infections, such as the common cold. In addition, linden and hyssop may promote a healthy fever and the immune system’s ability to fight infections. Yarrow is another diaphoretic that has been used for relief of sore throats, though it has not yet been researched for this purpose.

Boneset is another immune stimulant and diaphoretic that helps fight off minor viral infections, such as the common cold. In addition, linden and hyssop may promote a healthy fever and the immune system’s ability to fight infections. Yarrow is another diaphoretic that has been used for relief of sore throats, though it has not yet been researched for this purpose.

Herbs high in mucilage, such as slippery elm, mallow (Malvia sylvestris), and marshmallow, are often helpful for symptomatic relief of coughs and irritated throats. Mullein has expectorant and demulcent properties, which accounts for this herb’s historical use as a remedy for the respiratory tract, particularly in cases of irritating coughs with bronchial congestion. Coltsfoot is another herb with high mucilage content that has been used historically to soothe sore throats. However, it is high in pyrrolizidine alkaloids—constituents that may damage the liver over time. It is best to either avoid coltsfoot or look for products that are free of pyrrolizidine alkaloids.

Herbs high in mucilage, such as slippery elm, mallow (Malvia sylvestris), and marshmallow, are often helpful for symptomatic relief of coughs and irritated throats. Mullein has expectorant and demulcent properties, which accounts for this herb’s historical use as a remedy for the respiratory tract, particularly in cases of irritating coughs with bronchial congestion. Coltsfoot is another herb with high mucilage content that has been used historically to soothe sore throats. However, it is high in pyrrolizidine alkaloids—constituents that may damage the liver over time. It is best to either avoid coltsfoot or look for products that are free of pyrrolizidine alkaloids.

Meadowsweet has been used historically for a wide variety of conditions. It is reputed to break fevers and to promote sweating during a cold or flu. Meadowsweet contains salicylates, which possibly give the herb an aspirin-like effect, particularly in relieving aches and pains during a common cold. While not as potent as willow, which has a higher salicin content, the salicylates in meadowsweet do give it a mild anti-inflammatory effect and the potential to reduce fevers during a cold or flu. However, this role is based on historical use and knowledge of the chemistry of meadowsweet’s constituents; to date, no human studies have been completed with meadowsweet.

Elderberry has shown antiviral activity and thus may be useful for some people with common colds. Elder flowers are a traditional diaphoretic remedy for helping to break fevers and promote sweating during a cold. Horseradish has antibiotic properties, which may account for its usefulness in easing throat and upper respiratory tract infections. The resin of the herb myrrh has been shown to kill various microbes and to stimulate macrophages (a type of white blood cell).⁶⁵ Usnea has a traditional reputation as an antiseptic and is sometimes used for people with common colds.⁶⁶

Herbs high in mucilage, such as slippery elm, mallow (Malvia sylvestris), and marshmallow, are often helpful for symptomatic relief of coughs and irritated throats. Mullein has expectorant and demulcent properties, which accounts for this herb’s historical use as a remedy for the respiratory tract, particularly in cases of irritating coughs with bronchial congestion. Coltsfoot is another herb with high mucilage content that has been used historically to soothe sore throats. However, it is high in pyrrolizidine alkaloids—constituents that may damage the liver over time. It is best to either avoid coltsfoot or look for products that are free of pyrrolizidine alkaloids.

Eucalyptus oil is often used in a steam inhalation to help clear nasal and sinus congestion. It is said to work similarly to menthol, by acting on receptors in the nasal mucous membranes, leading to a reduction of nasal stuffiness.⁶⁷Peppermint may have a similar action and is a source of small amounts of menthol.

Red raspberry, blackberry, and blueberry leaves contain astringent tannins that are helpful for soothing sore throats.⁶⁸Sage tea may be gargled to soothe a sore throat. All of these remedies are used traditionally, but they are currently not supported by modern research.

Red raspberry, blackberry, and blueberry leaves contain astringent tannins that are helpful for soothing sore throats.⁶⁹Sage tea may be gargled to soothe a sore throat. All of these remedies are used traditionally, but they are currently not supported by modern research.

Herbal supplements can help strengthen the immune system and fight infections. Adaptogens, which include eleuthero, Asian ginseng, astragalus, and schisandra, are thought to help keep various body systems—including the immune system—functioning optimally. They have not been systematically evaluated as cold remedies. However, one double-blind trial found that people who were given 100 mg of Asian ginseng extract in combination with a flu vaccine experienced a lower frequency of colds and flu compared with people who received only the flu vaccine.⁷⁰

Herbs high in mucilage, such as slippery elm, mallow (Malvia sylvestris), and marshmallow, are often helpful for symptomatic relief of coughs and irritated throats. Mullein has expectorant and demulcent properties, which accounts for this herb’s historical use as a remedy for the respiratory tract, particularly in cases of irritating coughs with bronchial congestion. Coltsfoot is another herb with high mucilage content that has been used historically to soothe sore throats. However, it is high in pyrrolizidine alkaloids—constituents that may damage the liver over time. It is best to either avoid coltsfoot or look for products that are free of pyrrolizidine alkaloids.

Elderberry has shown antiviral activity and thus may be useful for some people with common colds. Elder flowers are a traditional diaphoretic remedy for helping to break fevers and promote sweating during a cold. Horseradish has antibiotic properties, which may account for its usefulness in easing throat and upper respiratory tract infections. The resin of the herb myrrh has been shown to kill various microbes and to stimulate macrophages (a type of white blood cell).⁷³ Usnea has a traditional reputation as an antiseptic and is sometimes used for people with common colds.⁷⁴

According to test tube experiments,⁷⁵ wild indigo stimulates immune function, which might account for its role in fighting the common cold and flu. In combination with echinacea, boneset, and homeopathic arnica, wild indigo has prevented and reduced symptoms of the common cold in double-blind research. Wild indigo is traditionally considered a strong antimicrobial agent, though it has not yet been investigated as an agent against cold viruses.

Traditional Chinese Medicine practitioners use Chinese artichoke (Stachys sieboldii), a species similar to wood betony (Stachys betonica), for colds and flu.⁷⁶ It is unknown whether wood betony would be useful for people with the common cold.

Boneset is another immune stimulant and diaphoretic that helps fight off minor viral infections, such as the common cold. In addition, linden and hyssop may promote a healthy fever and the immune system’s ability to fight infections. Yarrow is another diaphoretic that has been used for relief of sore throats, though it has not yet been researched for this purpose.

Caution: Using zinc nasal spray has been reported to cause severe or complete loss of smell function. In some of those cases, the loss of smell was long-lasting or permanent.⁷⁷

Zinc interferes with viral replication in test tubes.⁷⁸ The beneficial effect of zinc nasal sprays should be weighed against the potentially serious side effect of loss of smell. Since zinc supplements are also effective and do not carry such a risk, it is more advisable to take zinc orally. 

A double-blind trial showed a 74% reduction in symptom duration in people using a zinc nasal spray four times daily, compared with the 42 to 53% reduction reported in trials using zinc gluconate or zinc acetate lozenges.⁷⁹ The average duration of symptoms after the beginning of treatment was 2.3 days in the people receiving zinc, compared with 9.0 days in those receiving placebo. However, in another double-blind study, zinc nasal spray was no more effective than a placebo; in both groups the median duration of symptoms was seven days.⁸⁰