People Believe at Least One Medical Myth

We have a global crisis in health trust, and it’s not about lack of information. The problem is the lack of reliable information.

The Edelman 2026 Trust Barometer, an annual survey of trust in institutions across more than 28 countries, found that trust in health information has declined significantly over the past three years. Half or more of respondents said they had difficulty distinguishing credible health reporting from misinformation. They have largely avoided established health institutions and instead gravitate towards content from social media personalities and informal networks. Perhaps most striking: A large number of people said they had recently acted on health information that was later found to be false or misleading.

This report shows what health educators and public health researchers have been documenting for years: we are not suffering from a deficit of health content. We are drowning in it, and most of it is false.

Medical myths are not benign. “Sometimes people are delayed in treatment. Others lead to the misuse of medicines that make infections harder to treat. Some have directly contributed to the return of diseases we had almost eliminated. Understanding where these myths come from—and what the evidence actually shows—is one of the most practical things any person can do for their own health.

Here are six of the most persistent and consequential medical myths, which will be examined honestly.

Myth 1: Vaccines Cause Autism

Why do people think so?

This myth has one, clear source: a 1998 paper in the medical journal The Lancet by Andrew Wakefield. The paper proposed a connection between the measles, mumps, and rubella (MMR) vaccine and autism. The press had a field day, and it quickly spread among parents already on edge about the rising number of autism diagnoses.

The public heard too late that the study had serious methodological problems, that Wakefield had undisclosed financial conflicts of interest, and that no other researchers anywhere in the world could replicate the results. The Lancet fully retracted the paper in 2010. Wakefield lost his medical license. The co-authors disassociated themselves from the findings. The study was formally announced to be fraudulent.

But the myth outlived the paper that gave it birth.

What the evidence really tells us

Scientists have amassed some of the most closely scrutinized evidence on this question in all of modern medicine. Studies of millions of children in several countries have found no link between vaccines and autism.

A 2019 Danish cohort study published in the Annals of Internal Medicine tracked over 650,000 children and found no increased risk of autism among children who received the MMR vaccine, including those at higher risk for autism. A 2019 Danish cohort study published in the Annals of Internal Medicine tracked over 650,000 children and found no increased risk of autism among children who received the MMR vaccine, including those at higher risk for autism. The World Health Organization, the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics, and every major health authority in the world have reviewed this body of evidence and reached the same conclusion: vaccines do not cause autism. The World Health Organization, the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics, and every major health authority in the world have reviewed this body of evidence and came to the same conclusion: vaccines do not cause autism.

The real danger in believing it

In 2000, measles was declared eliminated in the United States. Since then, outbreaks have re-emerged in under-vaccinated populations, including a multi-state outbreak in 2019, the largest in nearly three decades. Measles can cause brain damage, deafness, and death, particularly in young children. The risks of mumps and rubella are serious. This belief that the MMR vaccine is harmful has led to real and preventable harm.

Myth 2: Antibiotics can treat viral infections

Why do people think so?

Antibiotics are incredible medicines. Antibiotics are incredible medicines. They transformed the treatment of bacterial infections that would have otherwise been fatal for most of the twentieth century. They transformed the treatment of bacterial infections that would have otherwise been fatal for most of the twentieth century. It is understandable that people want access to them when ill and associate them with getting better. It is understandable that people want access to them when ill and associate them with getting better.

Common experience, too, helps with the confusion. Many people have taken antibiotics when they have had a cold or flu and then recovered. The rational but wrong conclusion is that the antibiotics caused the recovery. In fact, they improved because the viral infection followed its natural course, as is typical for viral infections.

What the evidence really tells us

Antibiotics are used to kill or stop the growth of bacteria. They don't work on viruses. Viruses cause most sore throats, most chest infections, influenza, the common cold, and Covid-19. Treating these conditions with antibiotics does not cure the infection, exposes the patient to side effects, and contributes to a serious global health problem.

That problem is antimicrobial resistance, the process by which bacteria evolve to survive antibiotic treatment. The WHO lists antimicrobial resistance as one of the most significant threats to global health. Bacteria change when antibiotics are overused. This behavior makes real bacterial infections harder to treat, and some strains are now resistant to almost all of the antibiotics available.

The real danger in believing it

Asking a doctor to prescribe antibiotics for a cold or flu won't help you get better faster. Asking a doctor to prescribe antibiotics for a cold or flu won't help you get better faster. Such behavior increases the chances that when you really need antibiotics—for example, for bacterial pneumonia, a severe urinary tract infection, or a wound after surgery—they may not work as well as they should. Such behavior increases the chances that when you really need antibiotics—for example, for bacterial pneumonia, a severe urinary tract infection, or a wound after surgery—they may not work as well as they should. The CDC estimates that there are at least 2.8 million antibiotic-resistant infections in the U.S. every year, and more than 35,000 people die from these infections. The CDC estimates that there are at least 2.8 million antibiotic-resistant infections in the U.S. every year, and more than 35,000 people die from these infections.

Myth 3: Drinking Eight Glasses of Water a Day

Why do people think so?

This one is intriguing in that it doesn’t seem to have one source in dubious science. Most commonly, people cite a recommendation made in 1945 by the United States Food and Nutrition Board that most adults require about 2.5 liters of water daily. What the popular retelling failed to mention was the very next sentence: most of this quantity is in prepared foods. The “eight glasses” shorthand entered the popular health culture and has never left.

Since then, it’s been amplified by bottled water companies, wellness influencers, and health advice columnists, all of whom have a vested interest in getting us to drink more water.

What the evidence really tells us

Hydration needs are individual and changeable. Hydration needs are individual and change. They depend on body size, activity level, climate, diet, and general health. They depend on body size, activity level, climate, diet, and general health. A review in the American Journal of Physiology in 2002 examined the evidence for the eight-glasses rule and found no scientific basis for it as a universal prescription. A review in the American Journal of Physiology in 2002 examined the evidence for the eight-glasses rule and found no scientific basis for it as a universal prescription. And for most healthy people, drinking in response to thirst is a beneficial way to stay well hydrated—thirst is a finely tuned physiological signal, honed through hundreds of thousands of years of evolution. And for most healthy people, drinking in response to thirst is a beneficial way to stay well hydrated—thirst is a finely tuned physiological signal, honed through hundreds of thousands of years of evolution.

Water in food—especially in fruits, vegetables, soups, and other high-moisture foods—makes a significant contribution to total fluid intake.

The real danger in believing it

For most people the risk here is low inconvenience, not serious harm. But this myth is not entirely harmless. In a few cases, especially among endurance athletes who were advised to drink regardless of thirst, too much water has caused a dangerous condition called hyponatremia, in which sodium levels in the blood become too low. It has resulted in several marathon deaths. The real danger lies in normalizing strict health rules and ignoring your body’s cues, which are generally very accurate.

Myth 4: You Only Use 10% of Your Brain

Why people believe it

Versions of this idea have been attributed to Albert Einstein — though there is no credible evidence he ever said it — and to various psychologists and self-help writers over the last century. It persists partly because it is a comforting idea: most of your potential is untapped, and you could achieve far more if only you could access the other 90%.

The claim has been used to sell everything from brain-training software to dietary supplements to productivity programs.

What the evidence actually shows

Neuroimaging studies using functional MRI and PET scans show that virtually all areas of the brain are active at various times. Over the course of a day, essentially all of the brain's regions engage in some function. Even during sleep, significant brain activity continues. Different regions specialize in different tasks — movement, language, memory, vision — but there is no dormant 90% waiting to be unlocked.

Maintaining a large, metabolically expensive organ that serves no purpose for 90% of its capacity would be extraordinary from an evolutionary standpoint. The brain consumes roughly 20% of the body's total energy despite representing only about 2% of its weight. There would be enormous selection pressure against maintaining unused tissue.

The real risk of believing it

This myth is less likely to cause direct physical harm than the others on this list. Its risks are more about how it primes people to be susceptible to dubious products and claims. If you believe that unlocking unused brain capacity is possible, you become a target for supplements, programs, and devices that promise to do exactly that — most of which have no credible evidence of efficacy and some of which carry real costs, either financial or pharmacological.

Myth 5: Feed a Cold, Starve a Fever

Why do people think so?

This saying is at least sixteenth-century old and appears in English literature as early as 1574. The basic idea has shifted over the centuries—at times the advice was to eat to warm a cold body and at other times to cut down on eating to avoid “feeding” the heat of a fever. Anyway, the phrase has survived for centuries mostly because it rhymes and is easy to remember.

What the evidence really tells us

There is not enough evidence to support either part of this advice. There is no sufficient evidence for either part of this advice. A small study published in Clinical & Experimental Immunology in 2002 suggested a small immunological difference between eating and fasting in terms of what immune responses were activated. The effect was modest, and the research has not been consistently replicated or translated into clinical guidance. A small study published in Clinical & Experimental Immunology in 2002 suggested a small immunological difference between eating and fasting in terms of what immune responses were activated. The effect was modest, and the research has not been consistently replicated or translated into clinical guidance.

What is well known is that the body needs enough nutrition and hydration to mount an immune response to either a cold or a fever-causing infection. If you have a fever, your metabolism is racing, your body is working diligently, and it needs food. Limiting your food intake when you have a fever is unlikely to help and may make you feel worse.

The real danger in believing it

For most otherwise healthy adults, it just means inconvenience. However, poor nutrition during illness can significantly delay recovery and increase susceptibility to secondary infections, especially in young children, older adults, or people with underlying health conditions. A child who has a high fever and won't eat should be encouraged to eat small amounts of easily digestible foods and to stay well hydrated—not "starved" in deference to an old saying.

Myth 6: Herbal or Natural Remedies are Always Safe

Why do people think so?

There is a philosophical appeal to this belief; there is a linguistic appeal. In health culture, "natural" is a very positive word; it suggests purity, gentleness, and the absence of side effects from pharmaceutical drugs. The framing is logical: synthetic drugs are made by big companies, can have serious side effects, and are often costly. Something that grows from the ground seems more reliable.

The word “natural” is also widely used in marketing. The word “natural” is also widely used in marketing. It provides a complete paradigm—ancient wisdom, harmony with the body, and liberation from industrial medicine—without requiring any particular proof. It provides a complete paradigm—ancient wisdom, harmony with the body, and liberation from industrial medicine—without requiring any particular proof.

What the evidence really tells us

The word "natural" describes origin, not safety. The word "natural" describes origin, not safety. Many of the most poisonous substances known to medicine are natural in the extreme: arsenic, ricin (a product of the castor bean), botulinum toxin, and cyanide (found in apple seeds and bitter almonds). Many of the most poisonous substances known to medicine are natural in the extreme: arsenic, ricin (a product of the castor bean), botulinum toxin, and cyanide (found in apple seeds and bitter almonds). Digitalis, which comes from the foxglove plant, can lead to lethal cardiac arrhythmias if taken in the wrong dose. Digitalis, which comes from the foxglove plant, can lead to lethal cardiac arrhythmias if taken in the wrong dose.

Many herbal supplements can interact with prescription drugs in potentially harmful ways. St. John’s Wort, a popular treatment for depression, can reduce the effectiveness of blood thinners, some HIV medications, and oral contraceptives. Kava is used for anxiety, but there are documented cases of severe liver damage. The FDA banned ephedra, a popular weight-loss supplement, after tying it to heart attacks and strokes. Being plant-based does not mean being “safe” at any dose, “safe” with other substances, or “effective” for its marketed purpose.

The real danger in believing it

People who use herbal remedies for serious conditions, instead of as a complement to evidence-based treatment, may be putting off necessary care. Additionally, many supplements are not standardized, meaning the amount of active compound can vary widely from batch to batch and brand to brand. In the United States and several other countries, herbal supplements do not have to be proven safe or effective before sale. It is often a mistake to assume that because they are on a pharmacy shelf, they have been tested.

Corrections spread more slowly than misinformation.

Knowing that health myths are false is not enough to prevent their proliferation. To do so, it helps to understand why they spread in the first place.

Research in cognitive psychology and communications science has revealed several mechanisms that structurally favor false health claims over accurate corrections.

The first is emotional impact. False health claims often elicit an emotional response—fear, hope, outrage, or vindication. Probabilistic, contextual, or qualifying health information elicits weaker emotional reactions. On platforms ranked by engagement, emotional intensity is rewarded; misinformation travels faster and farther than corrections.

The second mechanism is known as the “illusory truth effect,” a well-documented phenomenon whereby repeated exposure to a claim increases the likelihood it will be judged as true, regardless of whether it has ever been verified. The second mechanism is known as the “illusory truth effect,” a well-documented phenomenon whereby repeated exposure to a claim increases the likelihood it will be judged as true, regardless of whether it has ever been verified. A health myth that you’ve heard fifteen times in different contexts becomes familiar, and familiarity is easily mistaken for credibility. A health myth that you’ve heard fifteen times in different contexts becomes familiar, and familiarity is easily mistaken for credibility.

The third is what researchers have called the “backfire effect”—though later studies have indicated that the phenomenon is more context-dependent than was once thought. The third is what researchers have called the “backfire effect”—though later studies have indicated that the phenomenon is more context-dependent than was once thought. But sometimes, directly challenging a deeply held false belief can make people believe it even more strongly. This phenomenon is because the challenge feels like an attack on their identity or judgment, rather than a correction of information. But sometimes, directly challenging a deeply held false belief can make people believe it even more strongly. This phenomenon is because the challenge feels like an attack on their identity or judgment, rather than a correction of information.

The fourth is asymmetrical reach. The fourth is asymmetrical reach. You can create a sensational health claim in seconds, like "this vaccine causes autism" or "this fruit cures cancer," and you don't need any evidence to support it. Then you can disseminate it globally within hours. You can create a sensational health claim in seconds, like "this vaccine causes autism" or "this fruit cures cancer," and you don't need any evidence to support it. Then, within hours, you can disseminate it globally. Correcting it requires research, peer review, clear communication, and then the far more difficult task of reaching people who have already seen and accepted the original claim. Correcting it requires research, peer review, clear communication, and then the far more difficult task of reaching people who have already seen and accepted the original claim. The correction is almost always later, slower, and less widely distributed than the claim it is correcting. The correction is almost always later, slower, and less widely distributed than the claim it is correcting.

That doesn’t mean corrections are futile. That means they need to be presented clearly, repeatedly, and without condescension.

A Practical Checklist for Assessing Health Claims

Ask yourself these questions before believing or sharing a health claim. You don’t have to be a doctor to use them. You just need a few minutes and a willingness to look.

• Kindly indicate who is claiming this and what their credentials are. An anonymous social media account making the same claim is not the same as a cardiologist making the same claim in a peer-reviewed journal. Note any conflicts of interest—who is funding the research or the person presenting it?

• Is it based on one study or a body of evidence? Is it based on one study or a body of evidence? One study, no matter how well designed, is a beginning and not an end. No matter how well designed, a single study is merely a beginning, not an end. When several independent studies all reach the same conclusion, you have strong evidence. When several independent studies reach the same conclusion, they provide strong evidence. Look for systematic reviews or meta-analyses. These summarize the results of many studies. Look for systematic reviews or meta-analyses. These summarize the results of many studies.

• Does the claim use absolute language similar to that used in scientific probability? In medical research, it is rare for anyone to say "this always works" or "this never causes harm." A good indicator is words like “this cures,” “this causes," or “doctors don’t want you to know."

• Is this a new claim? Has the claim been covered by established health organizations? Is this a new assertion? Has the claim been covered by established health organizations? New findings take time to reach the major health bodies. New findings take time to reach the major health bodies. If something is being widely circulated online but has not been mentioned by the CDC, WHO, NHS, or equivalent national health authority, that is something to note. If something is being widely circulated online but has not been mentioned by the CDC, WHO, NHS, or equivalent national health authority, that is something to note.

• Does the claim ask you to act quickly or skip regular medical care? Time is a trick of convincing. Anything with the phrases “act now before the remedy is banned” or “skip your doctor and try this first” should set off immediate skepticism.

• Do you know its original source? Many of these health claims refer to “a study” but do not name or link to it. If a source cannot be located, it may not exist in the form indicated by the description. PubMed (pubmed.ncbi.nlm.nih.gov) offers free access to peer-reviewed medical research.

• Does the claim affirm something you already want to believe? It is the hardest question to answer truthfully. We are all more open to claims that echo the views, fears, or hopes we already have. When a health claim seems to be validating everything you suspected, you need to scrutinize more, not less.

• Is this claim verified independently? Organizations like Snopes, Health Feedback, and the NHS Behind the Headlines service routinely check circulating health claims against the evidence available. A little research will save you a lot of time.

The Edelman findings serve as a reminder that misinformation is primarily not a problem of stupidity or bad faith. It's a structural problem, shaped by incentives, algorithms, cognitive shortcuts, and the real complexity of medical evidence. Most people who spread a medical myth do it because they think it’s true, and they want to help someone.

The best reply to that is not ridicule. Better information, given clearly and often.