Some health myths stick around no matter how many times experts bust them. Passed down through generations or spread online, these ideas sound right—but medical science says otherwise.
Here are 15 persistent health myths that have been completely debunked by doctors and scientists. You’ve probably heard them. Now, it’s time to leave them behind.
1. You Should Drink 8 Glasses of Water a Day
Staying hydrated is important, but the “8 glasses” rule is outdated. Your needs depend on your diet, activity, and climate. Many foods and drinks hydrate you, too.
2. Cracking Your Knuckles Causes Arthritis
There’s no link between knuckle cracking and arthritis. The sound comes from gas bubbles, not bone damage.
3. You Only Use 10% of Your Brain
Brain scans show we use nearly all parts of our brain—even while resting. This myth is pure science fiction.
4. Cold Weather Makes You Sick
Viruses make you sick, not cold air. People tend to catch more colds in winter because they stay indoors and in close contact.
5. You Can Sweat Out Toxins
Sweating cools your body but doesn’t remove toxins. Your liver and kidneys do the detoxing—no sauna or spin class required.
6. Feed a Cold, Starve a Fever
This old advice has no scientific basis. When you’re sick, the most important thing is to stay hydrated and eat if you can.
7. Sugar Makes Kids Hyper
Study after study shows no direct link between sugar and hyperactivity. Excitement and environment often explain the behavior.
8. Antibiotics Cure Everything
Antibiotics only treat bacterial infections—not viruses like colds or the flu. Using them incorrectly can lead to antibiotic resistance.
9. You Should Wait an Hour After Eating Before Swimming
There’s no evidence that swimming after eating causes cramps. As long as you feel comfortable, you’re fine to dive in.
10. Shaving Makes Hair Grow Back Thicker
Shaving cuts hair at the surface. It may look blunt as it grows back, but the texture and thickness don’t actually change.
11. Microwaves Cause Cancer
Microwaves use non-ionizing radiation, which doesn’t damage DNA like cancer-causing radiation does. They’re safe when used properly.
12. You Can “Catch Up” on Sleep
Sleeping extra on the weekend won’t fix long-term sleep debt. Consistent, nightly rest is what your body really needs.
13. Detox Diets Cleanse Your Body
Your body already detoxes itself through your liver and kidneys. Juice cleanses or detox teas won’t do the job better—and can even be harmful.
Read More: 10 Wellness Products That Are Just Expensive Placebos
14. You Need Daily Multivitamins
Most healthy people get what they need from food. Taking daily vitamins without a deficiency often adds no real benefit.
Read More: 10 Historical Myths the Movies Taught Us
15. Vaccines Cause Autism
This myth was based on a single, discredited study. Decades of research have proven there’s no link between vaccines and autism.
Believing myths can keep you from making the best choices for your health. Stick to facts, trust medical experts, and let go of outdated advice that doesn’t hold up to science.
Read More: 10 Debunked Myths Your Parents Convinced You Were Real
