“Feed a cold, starve a fever” is an adage that’s been around for centuries. The idea most likely originated during the Middle Ages when people believed there were two kinds of illnesses. The illnesses caused by low temperatures, such as a cold, needed to be fueled, so eating was recommended. Illnesses caused by high temperatures, such as a fever, needed to be cooled down, so refraining from eating was thought to deprive the furnace of energy.

Nowadays, most doctors and years of research into the cold and flu say there’s only one tried-and-true treatment for colds and flu — plenty of rest and fluids. That’s because colds and flu are caused by viruses, for which there is no cure. But you can support your immune system as it struggles to prevail through proper nutrition and, even more importantly, proper hydration­.

If anything, the adage should be, “feed a cold, feed a fever,” because bodies fighting illness need energy, so eating healthy food helps. Eating food when you have a cold can also help the body generate heat, although other methods of keeping warm, like wearing an extra layer of clothes or wrapping yourself in a blanket, do the trick as well.

There are many reasons you shouldn’t try to starve a fever. Fever is part of the immune system’s attempt to combat the virus. Fever raises body temperature, which increases metabolism and burns more calories. That’s one reason why taking in calories becomes important.

What’s far more crucial in combating both colds and the flu is staying hydrated. Fever dehydrates the body, in part through increased sweating from the elevated temperature. Vomiting and diarrhea, two common symptoms of the flu, also quickly dehydrate the body. Dehydration makes the mucus in the nose, throat, and lungs dry up, which can lead to clogged sinuses and respiratory tubes. When mucus hardens it becomes more difficult to cough, which is the body’s way of trying to expel mucus and the germs it contains.

Replacing fluids is critical to helping the body battle the virus. Water works just fine, as do fruit juices and electrolyte beverages. If you feel nauseated, try taking small sips of liquids, as gulps might cause you to throw up. You can be sure you’re getting enough fluids by looking at the color of your urine, which should be pale yellow, almost colorless.

Of course, when you’re sick, you may not feel much like drinking and even less like eating. Loss of appetite is common, and might be part of the body’s attempt to focus its energy on pounding the pathogens. Don’t force yourself to eat, but make sure to take in plenty of fluids. However, you should avoid coffee, caffeinated sodas, and alcohol, because caffeine and alcohol both contribute to dehydration.

Once you’ve contracted a cold or the flu, it should run its course in five to 10 days. And while nothing can cure a cold or the flu, some remedies can ease your symptoms and keep you from feeling so miserable.

Cold and Flu Remedies That Work

Wash your hands

For starters, frequent hand washing is one of the best things you can do to avoid catching whatever bugs might be going around. The key to making it count is using lots of soapy water and scrubbing for at least 20 seconds. If you're in a public restroom, use a paper towel instead of your bare hand when you touch the door handle. At home, you should regularly disinfect doorknobs with Lysol spray or disinfectant wipes. And don't forget about your germy computer keyboard and mobile phone. It's a good idea to regularly run a disinfectant wipe over those keys and your phone.

Sip warm liquids

Taking in warm liquids such as chicken soup, hot tea (with lemon or honey), or warm apple juice can be soothing and the warm vapor rising from the bowl or cup can ease congestion by increasing mucus flow. Chicken soup is everyone's favorite, but it's not a miracle cure. It does provide needed calories and salt, as well as some nutritional benefits. Chicken soup is also generally easy on the stomach.

Soothe a sore throat

Gargling with salt water helps get rid of the thick mucus that can collect at the back of the throat, especially after you've been lying down. It can also help ease stuffy ears. Use 1/4 to 1/2 teaspoon salt dissolved in an eight-ounce glass of warm water. Please note that children younger than 6 years old will be unlikely to be able to gargle properly.

You can also try ice chips, sore throat sprays, lozenges, or hard candy. Don't give lozenges or hard candy to children younger than 3 to 4 years old because they can choke on them.

Combat a stuffy nose

Over-the-counter saline nasal drops and sprays can help relieve stuffiness and congestion. In infants, experts recommend putting several saline drops into one nostril, then gently suctioning that nostril with a bulb syringe. Saline nasal sprays may be used in older children.

Another option to ease stuffiness is nasal irrigation with a neti pot, where you pour salt water into one nostril and let it run out the other, clearing out your nasal passages. You can buy pre-made saline solution or make it by mixing salt and lukewarm sterile or distilled water. Neti pots are available in health food stores and drugstores.

Add moisture to the air

Breathing moist air helps ease nasal congestion and sore throat pain. One good strategy is to indulge in a steamy shower several times a day — or just turn on the shower and sit in the bathroom for a few minutes, inhaling the steam. Another way to ease congestion is to use a steam vaporizer or a humidifier. Be sure to change the water daily and clean the unit often in order to be sure it’s free of mold and mildew.

Another quick way to open clogged airways is to make a “tent.” Bring a pot of water to a boil and remove it from the heat. Drape a towel over your head, close your eyes, and lean over the water under the “tent,” breathing deeply through your nose for 30 seconds. You may also want to add a drop or two of peppermint or eucalyptus oil to the water for extra phlegm-busting power. Repeat this as often as necessary to ease congestion.

Relieve Pain

For adults and children older than 5, over-the-counter decongestants, antihistamines, and pain relievers might relieve some symptoms. As far as pain relievers go, children six months or younger should only be given acetaminophen. For children older than six months, either acetaminophen or ibuprofen are appropriate. Adults can take acetaminophen, ibuprofen, or aspirin. Please note that none of these over-the-counter medications will prevent a cold or shorten its duration, and most have some side-effects.

Another great way to relieve headache or sinus pain is to place a warm cloth over your forehead and nose.

Rest

Your body needs time to heal, so listen to it. If your body’s urging you to spend all day in bed, then do so. Don't press on with daily chores in the face of severe cold or flu symptoms. And don’t skimp on nighttime sleep. Good sleep cycles help the immune system work well, so it’s important to get a full eight hours of sleep each night.