Age-old advice can sometimes be a very good thing. After all, some practices have stood the test of time and are still relevant today. However, for others, science marches on, and we learn healthier practices and cures. Still, myths like the five below persist–and may be doing more harm than good when used to improve your health.

Myth: Drink 8 glasses of water every day

Drinking plenty of water is essential. But eight glasses–that’s far more than we need! Science has not actually established the actual quantity, according to urgent care physician Dr. Kwame Asamoah. Plus, water comes from your food as well. A good rule of thumb is just to drink when you’re thirsty. If you aren’t thirsty, you’re probably getting adequate water.

Myth: Carrots help you see in the dark

The beta carotenes found in carrots become vitamin A in our bodies–the vitamin that helps our nerve impulses see light. This contributes to the myth that eating carrots may give you night vision, or better vision. However, too much beta carotene can stop lutein and zeaxanthin–also critical to vision–from working properly. This can start a chain reaction leading to cataracts and macular degeneration. Too many carrots won’t just not give you night vision; it can take away your regular vision, too!

Myth: Sitting too close to the TV ruins your eyesight

We’ve heard this since televisions became a household appliance. Sitting too close to a screen or holding your phone up to your face does cause eye strain, which includes pain around the eyes, fatigue, blurry vision, and headaches. But it does not actually damage your eyesight. Rather, this behavior is probably an indicator of preexisting nearsightedness. So while there’s a correlation, sitting too close to a screen is just the result.

Myth: Feed a cold, starve a fever

Another old wives’ tale tells us that when we have a cold, we should eat as much as we can to fight it off. Conversely, we should eat little or nothing when suffering from a fever. In actuality, it’s important to eat what healthy, infection-fighting foods you can whenever you’re sick. Your body will need its strength to fight off colds and fevers. Just be careful not to overeat and make yourself feel worse! It’s also important with both to stay well hydrated. Fevers and vomiting cause dehydration, so eating and drinking will help retain water.

Myth: Drinking milk is good for your bones

Drinking milk actually won’t make your bones stronger. Calcium is good for bone health, but milk–despite its high calcium content–won’t help. In fact, the vitamin A in milk can actually make your bones weaker! Rather, try eating leafy greens and sweet potatoes to get healthier calcium.