Can Emergen-C Actually Prevent a Cold?

Does Emercen-C work to prevent or treat colds? Unfortunately, the answer is unclear. Emergen-C is available as a fizzy powder—and also as gummies and chewables—that includes a mix of nutrients such as B vitamins and vitamin C. Emergen-C is advertised to offer "everyday immune support." While there is anecdotal evidence from users that it helps during cold and flu season, research provides mixed results.

Many studies have been conducted on its main ingredient, vitamin C, with mixed results. Because Emergen-C is a supplement, it can't make specific health claims. Its manufacturer settled a lawsuit in 2014 after it was accused of making health claims without actual evidence. Here's what you need to know.

Emergen-C Ingredients

Emergen-C's main ingredient is vitamin C. Some versions contain about 1,000 milligrams (mg) per packet, while others may vary. It's important to check specific product labels. There are approximately 500mg of vitamin C per gummy and 1,000mg per chewable. For comparison, many other OTC vitamin C supplements contain only 500mg per dose, and multivitamins may contain only around 60mg.

The Emergen-C immune support also contains the following ingredients:

• Antioxidants like zinc, vitamin E, and manganese
• B vitamins—thiamin, riboflavin, niacin, vitamin B6, folic acid, vitamin B12, and pantothenic acid
• Caffeine
• Electrolytes like sodium, calcium, phosphorus, magnesium, and potassium 
• Ginseng
• Melatonin
• Plant-based proteins
• Probiotics
• Superfoods
• Vitamin D
  

Does Emergen-C Work? What the Research Says

Emergen-C's claim to fame is the high dose of vitamin C, but the link between vitamin C and colds has been inconclusive. "The research has not been very high quality, and the results have been mixed," William Curry, MD, professor of medicine at the University of Alabama at Birmingham, told Health.

Some studies have found that vitamin C can help reduce the severity of cold symptoms. However, the vitamin may not have much more of a benefit. Vitamin C may not prevent colds in most people. However, in individuals under extreme physical stress, such as athletes, studies suggest it may reduce the incidence of colds. Additionally, vitamin C likely won't protect you if you're coming down with a more severe illness, like influenza.

The National Institute of Health recommends adults need a daily amount of 8 mg of zinc—a mineral helpful for the immune system—for adult females and 11 mg for adult males. Some studies have suggested zinc may speed up recovery from the common cold. However, for context, one Emergen-C packet only contains 2mg of zinc.

The other ingredients in Emergen-C may have antioxidant properties. Yet, Dr. Curry noted that there's no evidence they can directly protect against colds or other viruses.

Risks and Side Effects

Dietary supplements, like Emergen-C, are minimally regulated by the U.S. Food and Drug Administration (FDA) and can affect people differently. Their effects depend on factors like frequency of use and dosage.

The tolerable upper limit for vitamin C is 2,000 mg a day. While exceeding this limit may increase the risk of kidney stones in some individuals predisposed to kidney stones, the risk is not universal. Excess vitamin C may cause gastrointestinal problems like diarrhea, nausea, and stomach cramps.

If you decide to take Emergen-C, pay attention to the dosage, and don't exceed the upper limit of the supplement. It's best to limit Emergen-C to fewer daily doses. Additionally, be careful when taking it alongside other vitamin C supplements. Emergen-C recommends one packet, one chew, or three gummies daily.

Some studies have also suggested that vitamin C can interact with certain medicines, including statins and chemotherapy drugs. Consult a healthcare provider if you're unsure whether vitamin C might affect your current medication regimen.

Daily Recommended Value of Vitamin C

The recommended daily vitamin C intake is as follows:

• Adult males: 90 mg
• Adult females: 75 mg
• Lactating individuals: 120 mg
• Pregnant individuals: 85 mg
• Smokers: 35 mg more daily than nonsmokers

You don't need daily Emergen-C to achieve those levels. You can get vitamin C naturally from different foods, including:

• Broccoli
  
• Brussels sprouts
• Cantaloupe
• Grapefruit
• Kiwi
• Oranges
• Red and green peppers
• Strawberries
  

How Else To Support Your Immune System

If you choose to take Emergen-C or any other supplement, it should not replace food-based sources of vitamins and minerals. "The best way to keep your immune system strong is to eat healthfully, including vitamin C-rich produce, all the time," Cynthia Sass, MPH, RD, contributing nutrition editor, told Health.

Other ways to support your immune system include:

• Being physically active regularly
• Getting enough quality sleep
• Limiting alcohol use
• Maintaining a healthy weight
• Quitting, or not starting, smoking

You can safely take a vitamin C supplement during cold and flu season, but keep some things in mind. "As long as you're not taking enough to hurt yourself, and you recognize that the benefit is unclear, I don't have a problem with patients who use these products," noted Dr. Curry. "If your experience is that it's helpful for you, then that's great."

A Quick Review

Although many people take Emergen-C to prevent or shorten a cold, the scientific evidence showing it works is minimal. There's also mixed research about vitamin C's effectiveness in preventing or treating colds in the general population. 

If you still decide to take Emergen-C, keep it to one serving daily. To ensure it's appropriate for you to take, especially if you're taking other medications, talk with a healthcare provider before using the supplement.