Medical myths — sometimes they’re hilarious and sometimes they’re downright dangerous information. No matter how often they’re debunked, people will still believe them. Why? Because when you’re told something is true throughout your entire life, it can be difficult to change your mind — no matter how many facts come to light. And there will always be things we don’t understand. So we make up stories and myths to comfort us. Medical myths are no different. We want explanations. So we create them. We hear things. We spread them. After all, when was the last time you heard an interesting tidbit and did research to prove its validity before telling someone else what you heard? Probably not ever.

That’s how medical myths can spread. Now let’s look at a few of my favorites, including the one in our title here. I hope you enjoy this countdown of 10 medical myths and their corresponding truths.

10. You can’t digest chewing gum (or it will take 7 years).

You might have heard this when you were a kid. This little medical myth supposedly had to do with the gum being too sticky to be digested properly. Your digestive system is designed to deal with much worse. When it comes across something indigestible, like chewing gum, that doesn’t mean it stays in your stomach. It still passes through your body — and no, it won’t take 7 years.

Don’t believe me? Read this.

9. Your hair keeps growing even after you die.

No…. No, no, no! First of all, your hair is already dead, even while you’re still alive and kicking. The only part “alive” is what’s under your scalp. And your scalp is the key to this myth. Here’s why it can look like hair still grows a little bit after death — the body dehydrates and the scalp recedes. That exposes the portion of each hair strand that was previously hidden beneath the scalp. Our next myth has a similar debunking.

Don’t believe me? Read this.

8. If you shave, your hair will grow back faster.

This is just silly. When you shave, you’re essentially just cutting the strands of hair off where they’re level with your skin. You’re not doing anything that affects the growth rate below that skin. Why does it sometimes feel like you have stubble within minutes of shaving then? Well, remember how we mentioned a corpse’s dehydrated scalp receding to make it look like hair was growing after death? Your skin does something similar. If you shave when your skin is wet or moisturized or plumped up for any other reason, it expands over a tiny bit of the hair strands. You shave, and you do it flush with that plumped up skin. But when you dry off and cool down and your skin tightens back up, it pulls back away from the hair it was previously covering.

Don’t believe me? Read this.

7. Coffee will sober up a drunk.

This is one of our most dangerous medical myths in this list. Why? Because the last thing anyone needs is a drunk out on the roads driving because they had some coffee and they think they’re fine. They’re not. The caffeine in coffee can mask the sedative properties of alcohol to a degree. But that’s it. It’s not a cure for drunkenness. At best all you end up with is a wide-awake drunk. If you’ve had too much to drink, stay off the roads (coffee or not).

Don’t believe me? Read this.

6. Eating carrots will fix your eyesight.

There’s some truth to this myth. The nutrients in carrots are good for your eyes. The problem is when people assume they can fix problems with their eyesight by loading up on carrots. Once the damage is done, carrots aren’t going to cure what ails you.

Don’t believe me? Read this.

5. Fresh vegetables are better for you than frozen ones.

I can’t blame people for believing this. In fact, sometimes it’s true (such as if you pick your vegetable from your own organic garden in your backyard and eat them immediately). What makes the more general statement a myth is when you compare supermarket “fresh” vegetables with frozen ones. You’re probably actually getting the healthier option from the freezer section. Why? Because those vegetables are often frozen very soon after being harvested, whereas the vegetables in the produce section could have been sitting on a truck or in the store for days before you actually buy them. The frozen vegetables are therefore sometimes “fresher.”

Don’t believe me? Read this.

4. Everyone needs to drink 8 glasses of water every day.

Any time you see the word “everyone,” assume someone’s BSing you. Very little in this world applies to every person equally. That includes water consumption. No, not everyone needs to drink 8 glasses of water each day. Some people need less. Larger people and athletes might need even more. On top of that variation, you also have to consider that we get some of our required fluid intake from the foods we eat (especially if we eat a lot of fruits and vegetables). That counts towards our total. So do other types of drinks like coffee, tea, and juice. And yes… drinks with caffeine still count. While caffeine is a diuretic, you don’t lose as much fluid from that effect as you gain from having the drink. Drink when you’re thirsty. If you’re not, it doesn’t always mean you should force yourself. You might just be getting plenty of fluids in other ways.

Don’t believe me? Read this.

3. Bed rest is best for a back ache.

I used to believe this myth, and oh how I suffered for it! When we don’t feel well or when we’re in pain, sometimes our instinct is to lie down and rest until we feel better. Unfortunately that can sometimes do more damage than good. Studies have shown that getting back to movement faster actually speeds recovery, while staying in bed can hinder it.

Don’t believe me? Read this.

2. If you go outside without a coat (or hat, or in the rain, etc.), you’ll catch a cold.

I’ve always been a bit of an outwear rebel, much to my mother’s dismay. As a kid I often left home without a coat (even in the winter). Oh, I had plenty of them. I just didn’t want to be bothered. Even to this day you’ll rarely catch me with shoes on my feet — I wear flip flops unless there’s at least a half an inch of snow on the ground (with very few exceptions). If I could go out barefoot all the time, I probably would. And do you know what? I catch colds far less than anyone else I know! How can that be? Our parents and grandparents always told us that if we went out without our hat, or our boots, or our coats, or if we got soaked in the rain without an umbrella, we’d catch a cold. Hogwash! Here’s a simple fact: cold and wet weather cannot cause you to catch a cold. You can only catch a cold if you actually get a cold virus. When it’s cold season, it’s not about what you wear — it’s about avoiding those that could spread the virus. You can also help by regularly washing your hands. And on that note, when I finish this article, I think I might just go out and play in the rain — cold-free!

Don’t believe me? Read this.

1. Underwire bras can give you breast cancer.

Did you know some people really believe that wearing underwire bras can kill you because they think they lead to breast cancer? Here’s a very simplistic reasoning behind the myth — the bras supposedly squish up your nice little lymphatic system all day long, which causes toxins to accumulate, which leads to cancer. Well good news ladies (and the occasional underwire-wearing gent — oh, you know you’re out there). There has been no scientific data that proves this myth to be true. So no worries. You don’t have to give up your favorite bra to protect your breasts.

Don’t believe me? Read this.