Do these common cold remedies actually work?

Sometimes when you’re sick with a cold, you’ll try anything to make yourself feel healthy again. But some cold remedies—many with little science to support them—can actually make you feel worse instead of better.

Many of these cold “treatments” have been around for decades, if not centuries. Which ones have you tried?

Vitamin C

In the early 1970s, two-time Nobel prize winner Linus Pauling, PhD, championed the idea that megadoses of vitamin C—up to 18,000 mg daily—could help prevent or lessen the severity of symptoms or duration of the common cold. (Note: the recommended dietary allowance of vitamin C is just 75 mg for women and 90 mg for men.)

So, if a Nobel prize-winning scientist told you that taking lots of vitamin C would help treat your cold, he must be correct—right?

Not exactly. 

In the years since Dr. Pauling made his claims, researchers have shown that taking 200 mg (or more) of vitamin C per day doesn’t reduce the incidence of colds in the general population. On the contrary, it may actually make you more sick. Megadosing vitamin C can cause diarrhea, nausea, abdominal cramps, and other gastrointestinal disturbances.

However, the prophylactic use of 200 mg or more of vitamin C has been shown to modestly shorten the duration of colds by 8% in adults and 14% in children. Also, prophylactic use of high-dose vitamin C may reduce the incidence of colds in extreme athletes exposed to very cold environments and in people with marginal vitamin C status, such as the elderly and chronic smokers.

Taking vitamin C after the onset of cold symptoms, though, doesn’t shorten cold duration or reduce the severity of symptoms.

Feed a fever, starve a cold

The vintage adage “feed a fever, starve a cold” has been around for centuries. It implies eating plentifully if you have a fever but cutting back or fasting if you have a cold.

The phrase is half right. A wiser saying might be “feed a fever, feed a cold.”

Nutritional status has a “bona fide effect” on the immune response, researchers have found. Fasting and dehydration weaken the antiviral immune response. And, since most common colds and fevers are viral in nature, “starving” them is counterproductive.

The opposite also appears to be true: Eating promotes cell-mediated immunity, as demonstrated by a surge in the production of immune mediators.

So, when you’re sick—whether it’s a cold or a fever—eat up.

Drink plenty of fluids

Any doctor will tell you that you need to drink plenty of fluids when you’re sick with a cold. There’s only one problem with this advice: No research backs it up.

As a matter of fact, no randomized, controlled clinical trials have ever investigated whether drinking fluids can help in overcoming the common cold.

Moreover, the authors of a Cochrane Systematic Review of observational studies reported that increasing fluid intake in acute lower respiratory infections may actually cause harm. 

While drinking plenty of fluids won’t cure the common cold, it will help prevent dehydration. Sore throats, fevers, runny noses, and cold medicines escalate the body’s loss of fluid. And this loss of fluid—just like “starving” a cold—can hamper the immune system.

So, does drinking plenty of fluids improve your cold? Probably not. Does it keep your cold symptoms from getting worse? Yup.

Zinc lozenges

Taking zinc may shorten the duration of the common cold, but taking too much zinc can actually make you more vulnerable to illness.

“Some studies suggest that zinc lozenges or syrup (but not zinc dietary supplements in pill form) help speed recovery from the common cold and reduce its symptoms if taken within 24 hours of coming down with a cold,” according to the NIH. “However, more study is needed to determine the best dose and form of zinc, as well as how long it should be taken before zinc can be recommended as a treatment for the common cold.”

But, proceed with caution: Taking a zinc supplement along with quinolone or tetracycline antibiotics reduces the amounts of both zinc and the antibiotic that the body absorbs. So, don’t mix zinc with antibiotics.

Also, excess zinc consumption can actually lead to decreased immunity. Don’t go above the upper limit, which is 40 mg of zinc per day for adults. Extra zinc offers no beneficial effects in children, so avoid giving them zinc lozenges.

An apple a day

Does an apple a day really keep the doctor away? This old adage implies that eating apples on a daily basis can prevent you from getting sick. But does it work?

Surprisingly, no one ever studied this timeworn belief—until 2015, when researchers at the University of Michigan School of Nursing, Ann Arbor, MI, took a crack at it.

“Although some may jest, considering the relatively low cost of apples (currently $1.13 per pound of Red Delicious apples), a prescription for apple consumption could potentially reduce national health-care spending if the aphorism holds true,” they wrote in a JAMA Internal Medicine article.

Sadly, the researchers found that an apple a day did not keep the doctor away (ie, reduce doctor visits and healthcare services). But they did find that regular apple eaters used less prescription medication.

“Our findings suggest that the promotion of apple consumption may have limited benefit in reducing national healthcare spending. In the age of evidence-based assertions, however, there may be merit to saying, ‘An apple a day keeps the pharmacist away,’” the authors concluded.

However, apples should not be substituted for prescription medication, of course.

What cold remedies work without making you feel worse?

The “cures” for the common cold mentioned above work marginally at best and are harmful at worst. So, what remedies can help when you have a cold?

The number one “treatment” is to get plenty of rest, according to the Mayo Clinic. Also, a saltwater gargle can soothe a painful sore throat. Warm, comforting beverages like chicken broth or hot tea with honey can help loosen mucus and prevent dehydration. 

Last but not least, stay home from work or school to prevent infecting others.