We are entering 2018-19 flu season, so some of you have decided to get the seasonal flu vaccine because you know it is your best choice to prevent the flu. Or you are in the group that decided to forsake the flu vaccine because you buy into the easily-debunked myths of the anti-vaccine world. Instead, you depend upon flu treatments without evidence on whether those actually work.
In case you don’t know, the flu is a very dangerous disease despite some of the myths. In the USA, the CDC estimates that the flu season every year results in 12 to 56 thousand deaths and 140 to 710 thousand hospitalizations. It is not a trivial disease that can be easily ignored. Let me be frank – your best, and really, the only choice to prevent the flu is getting the seasonal flu vaccine. And, it is the only method to boost your or your children’s immune system against the flu.
I’ve written previously about various supplements and treatments for the common cold, and they mostly don’t work. Or the evidence is so weak that it’s a waste of money to use them. Or they’re just useless.
These ineffective treatments exist for one reason – money. Cold and flu treatments are a significant part of the estimated global US$278 billion supplement and nutraceutical industry. And the industry is largely unregulated, so they can make unsupported claims about things like flu treatments, and people buy them based on the pseudoscience and false claims.
Although there’s some overlap between the common cold and flu treatments, there are a large number of flu treatments that get sold over the counter, although one class of drugs are sold by prescription. Are any effective? Let’s find out.
The flu kills
As I mentioned above, the flu can lead to hospitalizations or death. But there’s more – this is what the CDC says about flu complications:
Most people who get influenza will recover in several days to less than two weeks, but some people will develop complications as a result of the flu. A wide range of complications can be caused by influenza virus infection of the upper respiratory tract (nasal passages, throat) and lower respiratory tract (lungs). While anyone can get sick with flu and become severely ill, some people are more likely to experience severe flu illness. Young children, adults aged 65 years and older, pregnant women, and people with certain chronic medical conditions are among those groups of people who are at high risk of serious flu complications, possibly requiring hospitalization and sometimes resulting in death. For example, people with chronic lung disease are at higher risk of developing severe pneumonia.
Sinus and ear infections are examples of moderate complications from flu, while pneumonia is a serious flu complication that can result from either influenza virus infection alone or from co-infection of flu virus and bacteria. Other possible serious complications triggered by flu can include inflammation of the heart (myocarditis), brain (encephalitis) or muscle (myositis, rhabdomyolysis) tissues, and multi-organ failure (for example, respiratory and kidney failure). Flu virus infection of the respiratory tract can trigger an extreme inflammatory response in the body and can lead to sepsis, the body’s life-threatening response to infection. Flu also can make chronic medical problems worse. For example, people with asthma may experience asthma attacks while they have the flu, and people with chronic heart disease may experience a worsening of this condition triggered by flu.
Without a doubt, the flu is a dangerous disease, but it is frequently ignored by most people, usually until they get sick. And don’t conflate the common cold with the flu – the common cold, though annoying, is not as dangerous or debilitating as the flu.
Given the dangers of the flu, we really do need to examine whether flu treatments have any value whatsoever.
Flu treatments that may or may not work
There are only three treatments that may actually work in treating you if you contract the flu – these are FDA-approved antiviral drugs, which are recommended by CDC this season, to treat influenza:
- Oseltamivir (trade name Tamiflu®), in the class of drugs called neuraminidase inhibitors, must be taken within 48 hours of the appearance of the first symptoms of the flu. Unfortunately, there is mixed evidence on the benefits of using this medication to treat the flu, including significant criticisms of the clinical trials. In a systematic review (considered the top of the hierarchy of medical research) of clinical studies of oseltamivir, the authors found that “there is no evidence that oseltamivir reduces the likelihood of hospitalization, pneumonia or the combined outcome of pneumonia.” On the other hand, another systematic review concluded that “oseltamivir and zanamivir are effective for prophylaxis” against the flu. When I see systematic reviews that are so diametrically opposed, it becomes difficult to see a scientific consensus about these drugs.
- Zanamivir (trade name Relenza®) is a neuraminidase inhibitor, similar to oseltamivir. A systematic review of all neuraminidase inhibitors has concluded that the risk for viral resistance, side effects, and financial cost outweigh the small benefits for prophylaxis and treatment of healthy individuals. It might be useful for those with high-risk factors from the flu.
- Peramivir (trade name Rapivab®) is a neuraminidase inhibitor similar to the other ones. It suffers from the same criticisms as all other neuraminidase inhibitors. However, some flu subtypes that have developed resistance to oseltamivir and zanamivir can be treated with peramivir.
Based on the best available evidence, especially for oseltamivir, which seems to indicate limited effectiveness combined with high cost, possible viral resistance, and side effects, it’s hard to justify recommending them for any patient except those individuals who are at high risk of complications to the flu.
Below are the CDC’s recommendation, who is more of an authority than I will ever be for flu treatment recommendations, for the use of these drugs:
It’s very important that antiviral drugs are used early to treat hospitalized patients, people with severe flu illness, and people who are at high risk of serious flu complications based on their age or health. Other people also may be treated with antiviral drugs by their doctor. Most people who are otherwise healthy and get the flu do not need to be treated with antiviral drugs.
Flu treatments that probably do not work
- Oscillococcinum is a homeopathic preparation, derived from Muscovy duck liver and heart (yes, you read that right), that is claimed to treat the flu. Because of the dilution, there are simply no molecules of duck guts in the homeopathy potion. Based on this ridiculous figurative and literal quackery (get it), one would not be surprised by a Cochrane systematic review that concludes, “There is insufficient good evidence to enable robust conclusions to be made about Oscillococcinum® in the prevention or treatment of influenza and influenza-like illness.” Homeopathy is pseudoscientific quackery.
- Zinc, heavily promoted by the company that makes Zicam, is often used to treat colds, in which there is some limited and very weak evidence in support of its use. There is some evidence that zinc supplementation for individuals who have a deficiency, extremely rare with a modern diet, can help resistance to some strains of flu. However, for those with no zinc deficiency, excess zinc has absolutely no effect.
- Vitamin D may be deficient in some individuals, especially during the winter. However, vitamin D supplementation appears to have no effect on the prevention or treatment of the flu or its complications.
- Garlic – there is no clinical evidence that garlic has any effect on preventing or treating the flu.
- Ginseng has been claimed to have some immune system benefits, but there’s no robust evidence that supports that. There is one primary research report (on the lower range of the hierarchy of biomedical science), that is unconfirmed by other research or clinical trials, which may indicate that ginseng has some effect on the flu virus. However, other than a highly biased and small clinical trial, there is no substantial evidence that ginseng has any effect on the flu.
- Echinacea has a substantial marketing effort, based on hype and anecdotes, supporting its use as a supplement. Systematic reviews have shown us that it has no effect on colds. A highly biased, poorly designed study was published in a low impact factor journal appears to show that echinacea may have an effect on the treatment of the flu. However, the evidence is unpersuasive, and there is no biological plausibility that echinacea has any effect on the flu.
- Elderberry – another herbal product that is claimed to have some effect on the prevention or treatment of the flu. However, a review of the research on elderberry treatment finds that there is only weak and limited evidence that it has an effect on the flu. However, more rigorous clinical trials are necessary to support a hypothesis that the fruit has any effect on the flu – this does not mean it will, it just means more evidence is required before you waste your money on this supplement.
- Vitamin C – simply put, there are no clinical trials, vigorous or otherwise, that have ever ever established that vitamin C has any effect on the course or treatment of the flu. Except in cases where an individual is deficient in vitamin C, very rare in today’s world, vitamin C supplementation has no effects on much of anything.
- Orthomolecular medicine is a form of alternative medicine (so, not real medicine supported by robust clinical evidence) that pushes the use of megadoses of vitamins and other micronutrients to combat all sorts of maladies. Generally, our physiology manages the amount of vitamins pretty efficiently, so extra vitamins simply get passed in the urine or stored for future use. There’s no magical process whereby extra vitamins “boost” your immune system. Not only do we lack any clinical data supporting the use of megavitamin therapy in the treatment of flu, but there is also evidence that megavitamins can actually cause increased risks from the complications of flu.
- Wheatgrass is one of the current food fads, in which there are dozens of claims at what it can do for health. In fact, there is no evidence that it can do anything for any disease, let alone the flu.
Scott Gavura at Science-Based Medicine wrote about a few more flu treatments, some of which made me chuckle, that are also making the rounds of the fake medicine universe. No, he didn’t find any that worked either.
You might think I’m being rather harsh about all of these flu treatments. But the problem is that for any real drugs to get real indications to prevent or treat flu, they have to undergo a difficult and challenging process of research and development, clinical trials and FDA review. Very few proposed pharmaceuticals that treat actual diseases get approved by drug governing bodies.
These supplements make unproven claims about their ability to treat or prevent the flu based on unrepeated animal or cell culture studies, or very weak, biased clinical trials published in very low ranked journals. They don’t even meet the minimum standards of evidence-based medicine.
On the other hand, actual medications that have gone through the clinical trial process (albeit, there are some significant criticisms of the clinical trials for these drugs) to determine if they have an effect on the flu. And they only show modest, at best, effectiveness in treating the flu.
The best choice we have is to reduce our risk of contracting the disease. And we do that with vaccines.
This article was first published in October 2017. It has been updated with current information along with some copyediting.
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