Emergen-C may help boost the immune system. However, evidence is lacking on whether it can treat and prevent colds.

Emergen-C may be worth taking as a general immune booster, but the jury is still out on whether it can help prevent or treat conditions like the common cold.

Here’s what you should know about its ingredients, purported uses, potential side effects, and more.

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Emergen-C is a supplement that people can take as a drink.

As the name suggests, Emergen-C’s main ingredient is vitamin C. Each serving (one 9.1 g packet) contains 1,000 milligrams (mg), or 1,667 percent of your recommended daily allowance (RDA).

Emergen-C also contains:

  • 10 mg of vitamin B-6 (500 percent of your RDA)
  • 25 micrograms (mcg) of vitamin B-12 (417 percent of your RDA)
  • 100 mcg of vitamin B-9 (25 percent of your RDA)
  • 0.5 mcg of manganese (25 percent of your RDA)
  • 2 mg of zinc (13 percent of your RDA)

The ingredients are said to:

  • Vitamin C can help boost immunity. It may also help create collagen to support healthy skin.
  • Vitamin B-6 may help metabolize red blood cells and fats, as well as help support a healthy nervous system.
  • Vitamin B-12 may help create red blood cells, which move oxygen around the body. It may also help metabolize food to create energy.
  • Folic acid helps support amino acid production.
  • Manganese helps support your overall immune system, as well as strengthen your skin and bones.
  • Zinc also helps boost immunity.
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Researchers have found limited evidence that vitamin C treats the cold or flu.

Although there’s some evidence to suggest that Emergen-C can help minimize the duration of your cold, research is limited.

One 2013 review of placebo-controlled trials found that taking vitamin C supplements regularly didn’t stop most people getting the cold.

However, the risk of getting the cold was halved in people exposed to short periods of extreme physical stress, such as marathon runners and skiers.

Researchers also found that regularly taking vitamin C supplements slightly reduced the duration of cold symptoms in the ordinary population.

One 2017 review of seven randomized trials found that using zinc lozenges may shorten cold duration by approximately 33 percent.

It’s important to note that these studies were done on specific ingredients found in Emergen-C, not the drink mix itself. More research is needed to determine whether Emergen-C offers the same benefits.

As for the flu, the National Center for Complementary and Integrative Health states that there isn’t strong evidence that any natural product can help treat or prevent the illness. Instead, they recommend the annual flu vaccine as the best means of prevention.

Although there’s reason to believe vitamin C supplements may have slight benefit, more research is needed to fully assess Emergen-C’s potential effects on sore throat, fatigue, and other health claims.

Sore throat

Taking vitamin C supplements regularly may slightly reduce the duration of cold symptoms, like a sore throat.

However, there isn’t any evidence that vitamin C supplements can help treat sore throat conditions like strep throat, tonsillitis, pharyngitis, and laryngitis.


One 2012 study analyzed the effects of intravenous vitamin C on fatigue in 141 office workers. Researchers found that intravenous vitamin C reduced fatigue within two hours of treatment, with the effect lasting for one day.

Weight loss

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A study found that vitamin C may help with weight loss.

Research on vitamin C supplementation and related weight loss has produced inconsistent results.

One 2006 small study of just 22 participants found that during a 60-minute walk on a treadmill, participants with low-blood concentrations of vitamin C burned 25 percent less fat than participants with adequate amounts of vitamin C.

However, researchers in a 2014 study found no sufficient evidence that vitamin C is linked to general changes in body weight.

Taking an increased amount of vitamin C for a short period of time is generally considered safe.

Vitamin C’s tolerable upper intake level (UL) is 2,000 mg per day for adults ages 19 and older.

Emergen-C packets contain 1,000 mg each. This means that you can probably still consume vitamin C through your diet without hitting the max UL.

Consuming 2,000 mg or more may cause:

Emergen-C contains far lower levels of all of the other vitamins and minerals on its ingredient list. No other ingredient comes this close to the respective UL for adults.

Talk to a doctor or other healthcare provider before use if you:

  • take prescription medication
  • are pregnant or breastfeeding
  • are postmenopausal
  • have diabetes
  • have hemochromatosis or other iron disorder

You shouldn’t use Emergen-C as your primary line of defense against the common cold, flu, or other conditions.

Emergen-C may be helpful as a temporary immune booster, but it shouldn’t be used long term. Instead, look to your diet.

If you eat the five recommended servings of fruits and vegetables each day, you should get more than 200 mg of vitamin C — well above your RDA. This can help keep your immune system in tip-top shape and help prevent illness in the long-run.

Medically reviewed by Dena Westphalen, PharmD on October 10, 2018 — Written by Claire Gillespie and Ana Gotter