Vitamin C for the Common Cold

At the very first sign of cold symptoms, many people reach for Vitamin C, whether in supplements, juices, cough drops, tea, or other forms.

Vitamin C was first touted for the common cold in the 1970s. But despite its widespread use, experts say there's very little proof that vitamin C actually has any effect on the common cold.

What Is Vitamin C?

Vitamin C is an important vitamin and antioxidant that the body uses to keep you strong and healthy. Vitamin C is used in the maintenance of bones, muscle, and blood vessels. Vitamin C also assists in the formation of collagen and helps the body absorb iron.

Vitamin C is found naturally in vegetables and fruits, especially oranges and other citrus fruits. This key vitamin is also available as a natural dietary supplement in the form of vitamin C pills and vitamin C chewable tablets.

Can Vitamin C Prevent or Treat Cold Symptoms?

Vitamin C has been studied for many years as a possible treatment for colds, or as a way to help prevent colds. But findings have been inconsistent. Overall, experts have found little to no benefit from vitamin C for preventing or treating the common cold.

In a July 2007 study, researchers wanted to discover whether taking 200 milligrams or more of vitamin C daily could reduce the frequency, duration, or severity of a cold. After reviewing 60 years of clinical research, they found that when taken after a cold starts, vitamin C supplements do not make a cold shorter or less severe. When taken daily, vitamin C very slightly shortened cold duration -- by 8% in adults and by 14% in children.

In 2010, researchers looked at all studies and found that taking vitamin C every day did not prevent the number of colds that a person got. In some cases, it made symptoms improve.

The results were different for people who were in very good physical condition, such as marathon runners. People like that who took vitamin C every day cut their risk of catching a cold in half.

So what does all this mean?

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According to this research, the average adult who suffers with a cold for 12 days a year would still suffer for about 11 days a year if that person took a high dose of vitamin C every day during that year.

For the average child who suffers about 28 days of cold illness a year, taking daily high-dose vitamin C would still likely mean about 24 days of cold illness.

When vitamin C was tested for treatment of colds in 7 separate studies, it was found to be no more effective than placebo at shortening the duration of cold symptoms.

If you take at least 0.2 grams of vitamin C every day, you're not likely to have fewer colds, but they may end a day or two quicker.

Is Vitamin C Safe to Take?

In general, vitamin C won't harm you if you get it by eating food like fruits and veggies. For most people, it's also OK if you take supplements in the recommended amount.

The RDA, or recommended daily allowance, is 90 milligrams for men and 75 milligrams for women. High doses of vitamin C (greater than 2,000 milligrams per day for adults) may cause kidney stones, nausea, and diarrhea.

If you're unsure about taking vitamin C for colds, talk to your health care provider.

WebMD Medical Reference Reviewed by Poonam Sachdev on September 24, 2021

Sources

SOURCES:

National Institute of Allergy and Infectious Diseases: "Common Cold."

PubMed: "Intake of Vitamin C and Zinc and Risk of Common Cold: A Cohort Study."

Mayo Clinic: "Cold Remedies: What Works, What Doesn't, What Can't Hurt."

Medscape: "Vitamin C May be Effective Against Common Cold. Primarily in Special Populations."

Douglas, R.M. The Cochrane Collaboration, 2007.

UpToDate: "The common cold in adults: Treatment and Prevention."

Medline Plus: "Flu" and "Common Cold."

NationalInstitutes of Health.

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