Quick Summary
What I'm going to do:- Never touch my eyes with my hands. I have contacts, so this is hard for me. But I can do it! UK NHS.
- Follow the darn 20-second hand-washing rule (note that hand-drying is also important!). There seem to be fewer studies on this than you'd think, given the prevalence and certainty with which this advice is commonly delivered. However, until I find evidence otherwise, there is at least some evidence that this scheme is effective, as opposed to me washing my hands for "as long as I feel like it" which is much less than 20 seconds. I also didn't know about the hand drying. [link to CDC summary, "Show me the Science - How to Wash Your Hands."]
- At least during cold season, take specific probiotics. (>= 15 billion CFU per day). Specifically, Lactobacillus and Bifidobacterium strains (e.g, L. paracasei, L. rhamnosus, L. acidophilus, B. lactis, B. bifidum). These aren't the only ones but I saw them a lot in RTI studies. Probiotics marketed for digestive health have different strains. I haven't found a magic blend yet, I just did my best at my local drug store to find one that had most of the above. I ended up with Nature's Bounty Probiotic 10 but I'm not happy that the amounts of each strain are not identified. Okay so why am I keen on these?
- In Hao et al.'s (2015) Cochrane systematic review (12 RCTs), it was found "Probiotics were found to be better than placebo in reducing the number of participants experiencing episodes of acute URTI by about 47% and the duration of an episode of acute URTI by about 1.89 days." They noted the quality of the evidence to be low due to poorly conducted trials, for example with unclear randomization, manufacturer involvement, and small sample sizes.
- In King et al.'s (2014) meta-analysis of 20 RCTs (12 with "low risk" of bias), the probiotics treatment group was sick for fewer days (as a group) and had shorter duration of illness (between .5 and 1 day) (Fig 3.)
- In Wang et al's (2016) meta-analysis of 23 trials involving children found those supplemented with probiotics had 10% less risk of getting an RTI (Fig 2), had fewer numbers of days of RTIs per person (-0.16 days) and had fewer numbers of days absent from day care/school compared with children who had taken a placebo (mean difference -0.96 days).
- Thinking about taking 600 - 1000mg Vitamin C, but I want to do more research first (see below). However if I see a bunch on sale I'll probably go for it. I do extreme exercise, sometimes :)
What about Vitamin C, Echinacea, Zinc, and other stuff?
One reason I'm listing stuff here is to show that meta-analyses and reviews DO tell you when things have not been shown to work, or when the evidence is poor. Case in point, Acetaminophen.Antihistimines
"Antihistamines have a limited short-term (days one and two of treatment) beneficial effect on severity of overall symptoms but not in the mid to long term. There is no clinically significant effect on nasal obstruction, rhinorrhoea or sneezing." (Cochrane Review 2015)Acetaminophen
"The data in this review do not provide sufficient evidence to inform practice regarding the use of acetaminophen for the common cold in adults." (Cochrane Review 2013)Antibiotics
A 2013 Cochrane Review analyzed 14 studies and found: "Antibiotics offer no benefit in the initial treatment of the common cold (acute upper respiratory tract infections (URTIs)). Antibiotics should not be given in the first instance as they will not improve the symptoms and adult participants will be affected by their adverse effects. Antibiotics offer no benefit for acute purulent rhinitis while there is an increase in adverse effects. However, if the symptoms persist for more than 10 days then antibiotic therapy may be beneficial (Morris 2007) and clinicians may wish to negotiate the use of them with patients, taking into account the resistance issues."C (Vitamin C)
I'm still thinking about this one. I'm either going to take 6000mg or nothing. There's a Cochrane Review (2013) of 29 studies, and the authors' conclusions were very mixed: "The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified, yet vitamin C may be useful for people exposed to brief periods of severe physical exercise. Regular supplementation trials have shown that vitamin C reduces the duration of colds, but this was not replicated in the few therapeutic trials that have been carried out. Nevertheless, given the consistent effect of vitamin C on the duration and severity of colds in the regular supplementation studies, and the low cost and safety, it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them. Further therapeutic RCTs are warranted."Echinacea
Wow, the Cochrane Review (2014) found 24 double-blind trials! Unfortunately, the authors' conclusions weren't good: "The most important recommendation for consumers and clinicians is to be aware that the available Echinacea products differ greatly. The overwhelming majority of these products have not been tested in clinical trials. It has been shown that labeling of products marketed in health food stores can be incorrect (Gilroy 2003). Our exploratory meta-analyses suggest that at least some Echinacea preparations may reduce the relative risk of catching a cold by 10% to 20%. A risk reduction of 15% would mean that if 500 out of 1000 persons receiving a placebo would catch a cold this figure would be 425 of 1000 persons with an Echinacea product. This is clearly a small effect of unclear clinical relevance. Furthermore, we cannot say which Echinacea products have an effect of this size, or a greater or lesser effect. While there are some hints that both alcoholic extracts and pressed juices that are based primarily on the aerial parts of E. purpurea have beneficial effects on cold symptoms in adults, the evidence for clinically relevant treatment effects is weak. There are still many remaining doubts due to the fact that not all trials using such preparations show even a trend towards an effect."Garlic
A Cochrane Review (2014) looked at 14 studies but only 1 met the criteria for review. That study"found that people who took garlic every day for three months (instead of a placebo) had fewer colds. That is, over the three-month period, there were 24 occurrences of the common cold in the garlic group, compared to 65 in the placebo group."
Nasal Decongestants
I'm gonna quit buying these. The big takeaway for me from the Cochrane Review (2016) is that for some reason, no one is actually studying the drug you can buy in the store ("pseudoephedrine is often replaced by phenylephrine as a way to control methamphetamine abuse. However, as a decongestant, phenylephrine may not be as effective (Eccles 2007). Despite phenylephrine being a common decongestant that is available over-the-counter, none of the included studies evaluated its effectiveness." The authors' conclusions regarding other decongestants: "There may be a small benefit on the subjective experience of nasal congestion after multiple doses of a nasal decongestant (low-quality evidence). However, it is unclear if the small effect is clinically relevant."Zinc
The Cochrane Review (2015) for this one was withdrawn! I'm including this piece of info to demonstrate one reason I'm a fan of Cochrane.Supplemental Information
Probiotics - why might they work?
"Potential underlying mechanisms of the action of probiotics on RTIs are not well defined yet. In addition to the local effects of competitively colonizing the gut to exclude potential pathogens, modulating the gut barrier function, and permeability, probiotics have been shown to have various immunomodulatory effects in the host.[62–64] It has been shown that probiotics can influence both innate and adaptive immune responses by producing exopolysaccharides.[65] A study showed that probiotics could increase the leukocyte, neutrophil, and natural killer cell counts and activity.[66] They also have been shown to be able to increase the expression of interleukin (IL)-10 and decrease the inflammatory cytokine expression, such as tumor necrosis factor-α, IL-1β, and IL-8.[67] Furthermore, probiotics can maintain higher salivary immunoglobulin A levels and produce bacteriocins and reuterin, which have antimicrobial activity.[68]" Wang et al. (2016)References
Center for Disease Control (CDC). 2015. "Show me the Science - How to Wash Your Hands". http://www.cdc.gov/handwashing/show-me-the-science-handwashing.htmlDe Sutter AIM, Saraswat A, van Driel ML. Antihistamines for the common cold. Cochrane Database of Systematic Reviews 2015, Issue 11. Art. No.: CD009345. DOI: 10.1002/14651858.CD009345.pub2.
Hao Q, Dong BR, Wu T. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database of Systematic Reviews 2015, Issue 2. Art. No.: CD006895. DOI: 10.1002/14651858.CD006895.pub3.
Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews 2013, Issue 1. Art. No.: CD000980. DOI: 10.1002/14651858.CD000980.pub4.
Jensen D, Schaffner D, Danyluk M, Harris L. Efficacy of handwashing duration and drying methods. Int Assn Food Prot Annual Meeting. 2012 July 22-25.
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 2014, Issue 2. Art. No.: CD000530. DOI: 10.1002/14651858.CD000530.pub3.
Kenealy T, Arroll B. Antibiotics for the common cold and acute purulent rhinitis. Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD000247. DOI: 10.1002/14651858.CD000247.pub3.
King, S., Glanville, J., Sanders, M. E., Fitzgerald, A., & Varley, D. (2014). Effectiveness of probiotics on the duration of illness in healthy children and adults who develop common acute respiratory infectious conditions: a systematic review and meta-analysis. The British Journal of Nutrition, 112(1), 41–54. http://doi.org/10.1017/S0007114514000075
Li S, Yue J, Dong BR, Yang M, Lin X, Wu T. Acetaminophen (paracetamol) for the common cold in adults. Cochrane Database of Systematic Reviews 2013, Issue 7. Art. No.: CD008800. DOI: 10.1002/14651858.CD008800.pub2.
Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database of Systematic Reviews 2014, Issue 11. Art. No.: CD006206. DOI: 10.1002/14651858.CD006206.pub4.
National Health Service (UK). Five facts about colds. http://www.nhs.uk/Livewell/coldsandflu/Pages/Fivefactsaboutcolds.aspx
