Every family has a keeper of the old wisdom. The aunt who insisted you’d catch your death going outside with wet hair. The grandfather who banned swimming until two hours after lunch.
The well-meaning adult who blamed your chocolate habit for every pimple. They said these things with complete conviction because someone said them with complete conviction to them, and so the chain continues.
Here are ten of the most enduring old wives’ tales, and what science actually has to say about them.
Feed a Cold, Starve a Fever (Or Is It the Other Way Around?)
Nobody can quite agree on the order, which should be the first clue that this advice is not grounded in rigorous research. The saying has existed in various forms since the 16th century, and it has been wrong the whole time.
Both colds and fevers increase your body’s demand for energy and fluids. A fever, in particular, raises your metabolic rate; your body is working hard, burning fuel to generate the heat it’s using to fight infection. Skipping meals deprives it of the resources it needs.
The advice you actually want: eat if you can, drink plenty of fluids regardless, and rest. The same prescription applies whether you have a fever, a cold, or both simultaneously, which is its own miserable experience.
Swimming After Eating Will Give You Cramps and Kill You
This one was delivered to generations of children with the gravity of a safety briefing. Eat your lunch, wait a full hour, some households insisted on two before you were permitted back in the water, lest you cramp up and drown.
The Red Cross, which has a professional interest in not having people drown, has confirmed that eating before swimming does not meaningfully increase the risk of cramping or any other danger.
A very large, very fatty meal might cause some discomfort during vigorous exercise, as digestion does divert blood flow, but this is true of any exercise and does not constitute a drowning risk.
The tale likely started from a genuine but exaggerated caution and was amplified by parents who wanted a peaceful post-lunch hour. Understandable, if not scientifically defensible.
Chocolate Causes Acne
Bad news for the chocolate industry, good news for chocolate lovers: this one is false. Acne is caused by a combination of sebum overproduction, bacterial activity, inflammation, and hormonal fluctuation, none of which are triggered by a square of dairy milk.
Large-scale studies have repeatedly failed to find a direct causal link between chocolate consumption and breakouts.
The myth likely took hold because adolescence, which is peak acne territory, is also peak chocolate consumption territory.
Correlation got mistaken for causation, and an entire generation was made to feel guilty about their snacks for no scientific reason. Diet can influence skin health in general ways, but chocolate is not the villain it was made out to be.
Carrots Will Improve Your Eyesight
This is one of history’s more successful pieces of wartime misinformation. During World War II, the British Royal Air Force was achieving remarkable results in intercepting German aircraft at night, largely thanks to newly developed radar technology.
To keep the radar secret, British intelligence promoted the story that their pilots owed their exceptional night vision to a diet rich in carrots. Apparently, the Germans found this plausible.
The general public found it plausible, too, and the association stuck. The truth is that vitamin A, found in carrots, is essential for producing the pigment that enables night vision, so a severe deficiency will impair your eyesight. But if you already have adequate vitamin A, eating more carrots will not sharpen your vision beyond its normal capacity.
No amount of carrots will correct a refractive error or let you read a number plate from further away. You have been lied to by wartime propaganda, and it worked on your parents.
Going Outside with Wet Hair Will Give You a Cold
This myth is so deeply embedded that it survives even among people who know, intellectually, that colds are caused by viruses. Cold air does not generate viruses.
Wet hair does not generate viruses. The only way to catch a cold is to come into contact with the relevant virus, typically through contact with an infected person or a contaminated surface.
The reason colds cluster in winter is social, not meteorological: people spend more time indoors, in closer proximity to one another, sharing recirculated air.
The virus spreads more easily. Your wet hair is irrelevant. You may feel cold and uncomfortable going outside with a wet head in January, which is a reasonable objection, but you will not get sick from it unless someone nearby is already sick.
Sitting Too Close to the TV Will Ruin Your Eyes
Parents deployed this one with particular urgency in the 1960s and 70s, when television sets were new enough to carry an air of technological menace.
The fear has since transferred to computer screens and phones. The underlying claim, that proximity to a screen causes permanent vision damage, is false.
Eye strain is real. Staring at any screen for extended periods causes temporary fatigue, dryness, and discomfort, and taking regular breaks genuinely helps. But this is reversible and causes no lasting damage.
The American Academy of Ophthalmology is clear that screen distance does not cause vision deterioration.
Children who sit very close to screens sometimes do so because they’re already shortsighted and are compensating, so proximity can be a symptom of a vision problem, not its cause.
Masturbation Causes Blindness
The origins of this myth are less medical than moral. It emerged from religious and social movements in the 18th and 19th centuries that were deeply invested in discouraging sexual activity, and “you’ll go blind” was an effective if entirely fabricated deterrent.
There is no physiological mechanism by which masturbation could affect vision. None has ever been proposed with any scientific seriousness.
Zinc deficiency can, in extreme cases, affect eyesight, and zinc is present in semen, but the quantities involved in normal sexual activity are nowhere near sufficient to cause deficiency, let alone blindness.
The myth persisted for centuries through shame and social pressure rather than evidence. It deserves to be retired permanently.
Cracking Your Knuckles Causes Arthritis
Already debunked in our science myths piece, but it bears repeating because this one is particularly immortal. The sound is produced by gas bubbles in synovial fluid, not by cartilage damage, nor by bones grinding together.
Dr. Donald Unger spent 60 years cracking the knuckles on one hand only, leaving the other as a control, and found zero difference in arthritis development. He won an Ig Nobel Prize for this commitment.
Arthritis has real causes: genetics, joint injury, age, and autoimmune conditions. Knuckle cracking is not among them. The myth survives because the sound is viscerally unpleasant and generates the kind of parental disapproval that tends to be remembered.
Spicy Food Causes Ulcers
For decades, people with ulcers were put on bland diets and told to avoid anything with flavor. The actual cause of most peptic ulcers, a bacterium called Helicobacter pylori, was only identified in the early 1980s by Australian physicians Barry Marshall and Robin Warren, who won the Nobel Prize for the discovery.
The other major cause is long-term use of anti-inflammatory medications like ibuprofen and aspirin.
Spicy food can irritate an existing ulcer, worsening symptoms, but it does not create ulcers in healthy stomach tissue.
The confusion is understandable: if eating chili makes your ulcer hurt, it seems intuitive that the chili is responsible. It isn’t. The bacteria got there first.
You Can Get Warts from Touching Toads
Toads do have bumpy, warty-looking skin, so the visual logic is understandable. But the resemblance is purely superficial.
Human warts are caused by specific strains of human papillomavirus, which are species-specific; they infect humans, not amphibians, and do not live on toad skin. The bumps on a toad are glands, not warts, and they cannot transmit HPV or any other human pathogen.
You can catch salmonella from handling reptiles and amphibians without proper hygiene, so washing your hands after handling toads is genuinely sensible advice.
But warts are not coming from the toad. They’re coming from other humans, via skin contact or contaminated surfaces. The toad is innocent.
Conclusion
Old wives’ tales are not stupid; they’re pattern recognition operating without enough data. People noticed that colds were more common in winter and made a reasonable but wrong inference about wet hair.
They noticed that adolescent chocolate binges coincided with breakouts and drew the obvious but incorrect conclusion. The tales made sense in the absence of better information, and they were passed down by people who genuinely wanted to help.
The problem is that the information improved, but the tales didn’t update. That’s what science is for… not to embarrass grandmothers, but to give us something more reliable than coincidence to go on.
