Natural Cold Remedies
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- NASAL IRRIGATION
- VITAMIN C
- VITAMIN D
- PELARGONIUM SIDOIDES
- HUMID AIR INHALATION
- HOMEOPATHIC REMEDIES
- EVERYTHING ELSE
WHAT ARE THEY?
The common cold (or simply “the cold”) is the most common infection in humans. It is an upper respiratory tract (nasal passages, mouth, and throat) infection caused by several different viruses. It presents with symptoms such as runny nose, sore throat, nasal congestion, sneezing, and cough. It is self-limited (it resolves on its own with time) and is typically mild in terms of severity .
The cold is a very bothersome illness. In the United States alone, it accounts for about 20 million days of school/work absence every year . It is also very uncomfortable and understandably leads people to seek relief in many different ways. For the same reason, the prospect of preventing a cold in the first place might be very appealing to some.
Many natural/alternative remedies are promoted for the prevention and treatment of the common cold. Given the unpleasantness of a cold, many such products are highly popular, and attract those looking to beat their symptoms before or after they start. Some of the most common remedies include:
Echinacea: a plant that is used in the preparation of herbal products. It is believed by some to have immune-system-enhancing medicinal effects. For the common cold, it is marketed for treatment and prevention.
Vitamin C: a dietary vitamin found in citrus fruits. Vitamin C supplementation is promoted for numerous health benefits, including prevention and treatment of the cold.
Vitamin D: another dietary vitamin, required for normal bone health. Often promoted as a “super vitamin”, some claim that vitamin D supplementation can strengthen the immune system. For colds, it is marketed for prevention.
Zinc: a metal (or “mineral”) that is required in small quantities for normal human health. Some people believe that zinc supplementation beyond dietary intake has immune-boosting effects. Zinc-containing products (most commonly zinc lozenges) are marketed for the treatment (and to a lesser extent, prevention) of the common cold.
Ginseng: the root of the Panax genus of plants, used in the preparation of herbal products. Ginseng is believed to possess many medicinal properties, including immune-boosting effects. Products containing ginseng are often marketed for the prevention and treatment of the cold. A highly popular (and arguably controversial) ginseng product in Canada is marketed under the brand name “COLD-FX”.
Garlic: a popular cooking spice from the plant Allium sativum. In addition to its culinary uses, garlic is believed by some to have medicinal properties (in the laboratory, it has known antimicrobial effects). For the common cold, garlic-containing health products are marketed for prevention and treatment.
Pelargonium sidoides: a plant that is used in the preparation of herbal products. Pelargonium is believed by some to have medicinal properties, especially in treating respiratory infections. Thus, it is marketed as a cold treatment.
Homeopathic Remedies: homeopathy is a system of alternative medicine. Its remedies are highly diluted compounds – so diluted that the final product is usually only water (for a further explanation, please see: Homeopathy). Homeopathic products are marketed for many purposes, including cold treatment and prevention.
Humid Air Inhalation: inhaling steam to relieve cold symptoms.
Nasal Irrigation: rinsing out your nasal passages with (usually) salt water. This may be in the form of a spray, squirt bottle, or “neti pot”. It is claimed to relieve cold symptoms.
DO THEY WORK?
Most natural cold remedies do not work.
What works: Handwashing works to prevent the common cold.
What might work: Nasal irrigation (salt water spray, neti pot, etc) might help relieve symptoms. Zinc may shorten the duration of colds, but the evidence is quite unclear, and negative side effects are common.
No reliable evidence that it works to prevent or treat the cold:
- Vitamin C
- Vitamin D
- Pelargonium sidoides
- Humid Air
- Homeopathic Remedies
- Chinese Medicinal Herbs
- Hot Liquids
- Essentially Everything Else
WHAT'S THE EVIDENCE?
Quick Definition: "Systematic Review"
A systematic review (and/or “meta-analysis”) is a scientific study that examines the agreement between many clinical trials. Instead of looking at a single study, systematic reviews attempt to analyse the totality of evidence related to a topic. By doing so, the true answer to a given question can be more accurately estimated. For example, a single study might indicate that a particular treatment is effective, leading readers to believe that this treatment works. However, what if three other studies conclude that the same treatment does not work? A systematic review might analyse the data from all four of these trials and conclude (correctly) that the totality of the evidence indicates that the treatment does not work (3 say no, only 1 says yes). The relative importance of each study is determined by things like study size (number of participants – more is better), chance for bias, consistency of measurements, and many others.
Because of their strength, systematic reviews are generally considered one of the highest standards of evidence. However, they are also not perfect, and are subject to the quality of the contributing clinical studies. Hence, if only low-quality studies are used, low-quality results will emerge (a.k.a. “garbage in, garbage out”).
What Works: Handwashing
Frequent handwashing is well-established as an effective way to prevent getting a cold. Systematic reviews of multiple clinical studies have demonstrated that handwashing – be it with soap or antiseptic agents such as alcohol-based hand sanitizers – reduces the spread of respiratory viruses (cold, flu, etc.) [2-4]. In fact, handwashing is a central component of infection-control programs in hospitals and is arguably more effective than any other method of routine prevention.
The Centers for Disease Control and Prevention (CDC) recommend washing your hands with soap and water instead of alcohol-based hand sanitizers, whenever possible .This is because hand-sanitizers kill many, but not all, microorganisms. Washing with soap and water better ensures that you physically remove tough germs from your hands. However, if you do use hand-sanitizer, it should be alcohol-based and at a concentration of at least 60% alcohol (60-95% is best).
What Might Work: Nasal Irrigation and Zinc
The evidence supporting nasal irrigation for cold symptom-relief is relatively weak. A systematic review of multiple clinical studies found that one “larger” trial (401 patients, age 6-10) suggested that a significant reduction in cold symptoms could be achieved with nasal saline (salt water) irrigation . This included reductions in nasal secretions, sore throat, and nasal obstruction. However, given the lack of any high-quality trials, confidence in the true effectiveness of nasal irrigation is questionable.
Systematic reviews based on the results of multiple clinical trials have determined that zinc may be effective for reducing the duration of colds [7-8]. When taken orally (by mouth) within 24 hours of symptom onset, zinc appears to reduce how long colds last, but not the severity of their symptoms . Adverse side effects are also common, including a bad taste and nausea [7-8]. There is also currently no reliable evidence to suggest that regular zinc supplementation can prevent colds from occurring in the first place .
The authors of these systematic reviews caution that the trials included in their analyses were relatively inconsistent (heterogeneous), so the true effectiveness of zinc is difficult to estimate. As a result, the actual value of zinc for treating colds remains unclear . When considering this uncertainty and the fact that adverse effects are common, some authors doubt whether the potential benefits of zinc are worth its unpleasantness .
It should also be noted: zinc products administered nasally (i.e. intranasal sprays) are not recommended, as they can cause permanent loss of smell [9-10].
No Reliable Evidence That It Works To Prevent Or Treat The Cold:
A systematic review assessing the agreement between 24 clinical studies found no reliable evidence that Echinacea products can effectively treat or prevent the cold [11-12]. None of the studies showed a reduction in cold occurrence with Echinacea use. Likewise, no convincing evidence was found to suggest that Echinacea products can reliably treat cold symptoms or reduce the duration of a cold [11-12]. Simply put: there is little to no reason to believe that Echinacea works for colds.
A systematic review of dozens of clinical trials demonstrated that regular supplementation with vitamin C has no effect on the chance that an average person will get a cold . The same study also found that vitamin C was unable to reliably treat a cold after its onset (i.e. only taking vitamin C when you have a cold does not work as a treatment). However, regular vitamin C supplementation was found to slightly reduce the duration of colds, but the relevance of the effect was questioned by the study’s authors . Essentially, an average adult would need to take vitamin C every day (i.e. 365 days a year) in order to achieve an 8% reduction in the duration of any colds they may get. This means that if a cold normally lasts 7 days, its duration would only be reduced by a fraction of a day. Whether or not consuming vitamin C supplements every day is worth less than a day’s reduction in cold symptoms may be a relevant consideration for consumers. Overall, however, the evidence does not suggest that vitamin C can prevent or treat the common cold .
Several clinical trials have assessed the ability of vitamin D to prevent upper respiratory tract infections [14-15]. Overall, vitamin D supplementation did not reduce the occurrence of colds. In other words, there is no reason to believe that vitamin D can prevent colds.
A systematic review of clinical trials of ginseng products for the prevention and treatment of colds found no reliable evidence to suggest that ginseng works for these purposes . The study concluded that there is insufficient evidence to support the use of ginseng for cold prevention, and that no evidence exists to suggest that ginseng can be taken as a treatment after a cold has already started. Two of the included trials seemed to suggest that constant supplementation with ginseng (i.e. taking it every day for 16 weeks) might reduce the duration of any colds caught during that time. However, the results were relatively poor quality, as the trial reporting the largest effect was very small (only 43 participants, average age of participants = 69 years old) and was published nearly a decade after it was actually performed (a questionable delay in publishing). Additionally, the reduction in cold duration was only observed when data from the second half of the study was analysed (i.e. no reduction was seen in the first 8 weeks or overall). In other words, the researchers had to ignore half of the data in order to find something interesting. This type of practice reduces the reliability of a study. Thus, as echoed by other doctors and researchers, the true effectiveness of ginseng for reducing cold duration is highly questionable .
In short: there is currently no good reason to believe that ginseng products can prevent or treat the cold.
A systematic review of the evidence supporting the use of garlic for the prevention and treatment of the common cold found only one study that was deemed worthy of attention (due to lack of quality of other studies) . This small study (146 participants) found that garlic appeared to reduce the occurrence of cold when taken daily for 12 weeks. Unfortunately, due to flaws in its design, even this “best” study was found to be questionable. For example, the measurement of “cold occurrence” was done in an unreliable way: participants were given a diary and instructed to record when they thought they had a cold. Thus, the determination of having a cold was a matter of personal opinion (a subjective measure), as opposed to a standardized observation by a third party. This, in addition to other concerns, led the authors to conclude that the study was of uncertain importance. As a result, the review concluded that there is no reliable evidence to recommend garlic for the prevention or treatment of the common cold.
A 2013 systematic review of Pelargonium sidoides for the treatment of acute respiratory infections found only one relevant study relating Pelargonium to the treatment of the common cold . This single small study (103 participants) found a benefit to using Pelargonium for reducing cold symptoms, but only after 10 days of treatment. For treatment after 5 days, no benefit was noted. Unfortunately, this study was also of very low quality, so its results were deemed highly uncertain. Overall, the authors of the review concluded that there is little reliable evidence to suggest that Pelargonium works for acute respiratory infections in general. For the common cold specifically, no reliable evidence exists.
Humid Air Inhalation
After considering the available clinical trials, a 2013 systematic review concluded that steam inhalation (heated, humidified air) could not be recommended for the treatment of colds . The results of the clinical studies were highly inconsistent – some showed benefit with steam treatment, while others did not. The trials were also quite small, leading to greater uncertainty for those showing improvement with steam. Therefore, overall, there is no reliable evidence to support humid air inhalation for the treatment of colds.
Homeopathic remedies do not work for the prevention or treatment of any condition, including the common cold . In 2015, a comprehensive analysis of 57 systematic reviews of homeopathy (representing 176 individual clinical studies that assessed 61 different health conditions) was conducted by the Australian Government’s National Health and Medical Research Council (NHMRC). This analysis concluded that there are “no health conditions for which there is reliable evidence that homeopathy is effective” . These remedies simply do not work.
For more information about homeopathy, please see: Homeopathy
For essentially every other proposed natural cold remedy, there is little to no reliable evidence to support their use. This includes Chinese medicinal herbs , acupuncture, and hot liquids [17, 23].
SUMMARY OF NATURAL COLD REMEDIES
TOO LONG; DIDN'T READ!
What works: Handwashing (for cold prevention)
What might work: Nasal irrigation (for symptom relief) and zinc (to shorten the duration of colds).
What probably (or absolutely) does not work: Everything else.
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2) Jefferson T, Del Mar CB, Dooley L, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database of Systematic Reviews. July 2011. doi:10.1002/14651858.cd006207.pub4.
3) Aiello AE, Coulborn RM, Perez V, Larson EL. Effect of hand hygiene on infectious disease risk in the community setting: A Meta-Analysis. American Journal of Public Health. 2008;98(8):1372–1381. doi:10.2105/ajph.2007.124610.
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5) CDC. Show me the science - when & how to use hand sanitizer. http://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html.
6) King D, Mitchell B, Williams CP, Spurling GK. Saline nasal irrigation for acute upper respiratory tract infections. Cochrane Database of Systematic Reviews. April 2015. doi:10.1002/14651858.cd006821.pub3.
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8) Singh M, Das R. Zinc for the common cold. The Cochrane database of systematic reviews. June 2013. http://www.ncbi.nlm.nih.gov/pubmed/23775705.
9) FDA. Warnings on Three Zicam Intranasal Products. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm166931.htm.
10) Davidson TM, Smith WM. The Bradford Hill criteria and zinc-induced Anosmia. Archives of Otolaryngology–Head & Neck Surgery. 2010;136(7):673. doi:10.1001/archoto.2010.111.
11) Karsch-Völk M, Barrett B, Kiefer D, Bauer R, Ardjomand-Woelkart K, Linde K. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews. February 2014. doi:10.1002/14651858.cd000530.pub3.
12) Karsch-Völk M, Barrett B, Linde K. Echinacea for preventing and treating the common cold. JAMA. 2015;313(6):618. doi:10.1001/jama.2014.17145.
13) Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. January 2013. doi:10.1002/14651858.cd000980.pub4.
14) Murdoch DR, Slow S, Chambers ST, et al. Effect of vitamin D 3 Supplementation on upper respiratory tract infections in healthy adults. JAMA. 2012;308(13):1333. doi:10.1001/jama.2012.12505.
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16) Seida JK, Durec T, Kuhle S. North American (Panax quinquefolius) and Asian ginseng (Panax ginseng) preparations for prevention of the common cold in healthy adults: A systematic review. Evidence-Based Complementary and Alternative Medicine. 2011;2011:1–7. doi:10.1093/ecam/nep068.
17) Allan GM, Arroll B. Prevention and treatment of the common cold: Making sense of the evidence. Canadian Medical Association Journal. 2014;186(3):190–199. doi:10.1503/cmaj.121442.
18) Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database of Systematic Reviews. November 2014. doi:10.1002/14651858.cd006206.pub4.
19) Timmer A, Günther J, Motschall E, Rücker G, Antes G, Kern WV. Pelargonium sidoides extract for treating acute respiratory tract infections. Cochrane Database of Systematic Reviews. October 2013. doi:10.1002/14651858.cd006323.pub3.
20) Singh M, Singh M. Heated, humidified air for the common cold. Cochrane Database of Systematic Reviews. June 2013. doi:10.1002/14651858.cd001728.pub5.
21) National Health and Medical Research Council. NHMRC Information Paper: Evidence on the effectiveness of homeopathy for treating health conditions. Canberra: National Health and Medical Research Council. 2015. Available at: https://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/cam02a_information_paper.pdf
22) Zhang X, Wu T, Zhang J, Yan Q, Xie L, Liu GJ. Chinese medicinal herbs for the common cold. Cochrane Database of Systematic Reviews. January 2007. doi:10.1002/14651858.cd004782.pub2.
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24) Allan GM, Cranston L, Lindblad A, et al. Vitamin D: A narrative review examining the evidence for Ten beliefs. Journal of General Internal Medicine. 2016;31(7):780–791. doi:10.1007/s11606-016-3645-y.