Emergen-C is a nutritional supplement that contains vitamin C and other nutrients designed to boost your immune system and increase energy.

It can be mixed with water to create a beverage and is a popular choice during cold and flu season for extra protection against infections.

However, many people wonder about its effectiveness.

This article reviews the science behind Emergen-C to determine if its health claims hold true.

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Emergen-C is a powdered supplement containing high doses of B vitamins, as well as vitamin C — reportedly to improve your immune system and energy levels.

It comes in single-serving packets meant to be stirred into 4–6 ounces (118–177 ml) of water before consumption.

The resulting beverage is slightly fizzy and provides more vitamin C than 10 oranges (1, 2).

The original Emergen-C formulation comes in 12 different flavors and contains the following (1):

  • Calories: 35
  • Sugar: 6 grams
  • Vitamin C: 1,000 mg, or 1,667% of the Daily Value (DV)
  • Vitamin B6: 10 mg, or 500% of the DV
  • Vitamin B12: 25 mcg, or 417% of the DV

It also provides 25% of the DV for thiamine (vitamin B1), riboflavin (vitamin B2), folic acid (vitamin B9), pantothenic acid (vitamin B5) and manganese, as well as smaller amounts of niacin (vitamin B3) and other minerals.

Other Emergen-C varieties are also available, such as:

  • Immune Plus: Adds vitamin D and extra zinc.
  • Probiotics Plus: Adds two probiotic strains to support gut health.
  • Energy Plus: Includes caffeine from green tea.
  • Hydration Plus and Electrolyte Replenisher: Gives extra electrolytes.
  • Emergen-zzzz: Includes melatonin to promote sleep.
  • Emergen-C Kidz: A smaller dose with a fruity flavor designed for kids.

If you don’t like fizzy drinks, Emergen-C also comes in gummy and chewable forms.

Summary Emergen-C is a powdered drink mix that contains vitamin C, several B vitamins and other nutrients to support energy levels and immune function.

Since Emergen-C supplies nutrients that interact with your immune system, many people take it to fend off colds or other minor infections.

Here is an in-depth look at each of Emergen-C’s major ingredients to determine whether the contained vitamins and minerals really boost immunity and increase energy levels.

1. Vitamin C

Each serving of Emergen-C contains 1,000 mg of vitamin C, which is much more than the RDA of 90 mg per day for men and 75 mg per day for women (1, 3).

However, research is mixed on whether large doses of vitamin C can prevent or shorten the duration of colds or other infections.

One review found that taking at least 200 mg of vitamin C daily only reduced one’s risk of cold by 3% and its duration by 8% in healthy adults (4).

However, this micronutrient may be more effective for people under high levels of physical stress, such as marathon runners, skiers and soldiers. For these people, vitamin C supplements cut the risk of colds in half (4).

In addition, anyone who is deficient in vitamin C would benefit from taking a supplement, since vitamin C deficiency is linked to increased risk of infections (5, 6, 7).

Vitamin C likely has such effects due to accumulating inside various types of immune cells to help them fight infections. Keep in mind that research into vitamin C’s mechanisms is ongoing (8, 9).

2. B Vitamins

Emergen-C also holds many B vitamins, including thiamine, riboflavin, niacin, folic acid, pantothenic acid, vitamin B6 and vitamin B12.

B vitamins are needed in order for our bodies to metabolize food into energy, so many supplement companies describe them as energy-boosting nutrients (10).

One of the symptoms of B vitamin deficiency is general lethargy, and correcting the deficiency is associated with improved energy levels (11).

However, it is unclear whether supplementing with B vitamins amplifies energy in people who are not deficient.

Certain deficiencies do harm your immune system. Insufficient levels of vitamins B6 and/or B12 can reduce the number of immune cells your body produces (12, 13).

Supplementing with 50 mg of vitamin B6 per day or 500 mcg of vitamin B12 every other day for at least two weeks has been shown to reverse these effects (14, 15, 16).

While studies indicate that correcting a B vitamin deficiency can boost immunity, more research is needed to understand whether supplementing has any effect on non-deficient, healthy adults.

3. Zinc

Some evidence suggests that taking zinc supplements can shorten the duration of a cold by an average of 33% (17).

This is because zinc is needed for the normal development and function of immune cells (18).

However, the amount of zinc in Emergen-C may not be enough to have these immune-boosting effects.

For example, one serving of regular Emergen-C contains just 2 mg of zinc, while clinical trials use much higher doses of at least 75 mg per day (17).

While the Immune Plus variety of Emergen-C gives a slightly higher dose of 10 mg per serving, this still falls short of the therapeutic doses used in research studies (19).

4. Vitamin D

Interestingly, many immune cells feature high numbers of vitamin D receptors on their surfaces, suggesting that vitamin D plays a role in immunity.

Several human studies have determined that supplementing with at least 400 IU of vitamin D daily can reduce your risk of developing a cold by 19%. It’s especially beneficial for people who are vitamin D deficient (20).

While original Emergen-C does not contain vitamin D, the Immune Plus variety boasts 1,000 IU of vitamin D per serving (17, 19).

Given that approximately 42% of the US population is deficient in vitamin D, supplementing may be beneficial for many people (21).

Summary There is some evidence that the ingredients in Emergen-C can improve immunity in people who are deficient in those nutrients, but more research is needed to determine whether similar benefits apply to non-deficient, healthy adults.

Emergen-C is generally considered safe, but there may be side effects if you’re taking it in high doses.

Ingesting more than 2 grams of vitamin C can trigger unpleasant side effects including nausea, abdominal cramps and diarrhea — and may increase your risk of developing kidney stones (22, 23, 24, 25).

Similarly, taking more than 50 mg of vitamin B6 every day for an extended period can cause nerve damage, so it’s important to watch your intake and monitor for symptoms like tingling in your hands and feet (26).

Regularly consuming more than 40 mg of zinc per day can cause copper deficiency, so it’s crucial to pay attention to how much you’re consuming from food and supplements (27).

Summary Consuming Emergen-C in moderation is likely safe, but excessive doses of vitamin C, vitamin B6 and zinc can cause unpleasant side effects.

While staying nourished is an important part of boosting immunity, there are other factors to consider. Here are other things you can do to strengthen your immune system.

Improve Gut Health

Maintaining a healthy gut can go a long way towards boosting immunity.

The bacteria in your gut interact with your body to promote a healthy immune response (28, 29, 30).

There are many things you can do to encourage the growth of good gut bacteria, including:

  • Eating a fiber-rich diet: Fiber is a food source for your gut bacteria. When bacteria consume fiber, they produce compounds like butyrate that fuel colon cells and keep your intestinal lining healthy and strong (31, 32, 33).
  • Consuming probiotics: Probiotics — bacteria that are good for your gut — can be consumed as supplements or via fermented foods like kimchi, kefir and yogurt. These bacteria can rebalance your gut and boost immunity (34, 35).
  • Reducing intake of artificial sweeteners: New research links artificial sweeteners to a negative impact on your gut. These sweeteners can lead to poor blood sugar management and unbalanced gut bacteria (36, 37).

Exercise Regularly

Research has found that regular exercise can strengthen your immune system and reduce the likelihood of getting sick (38).

This is at least in part because moderate exercise reduces inflammation in your body and protects against the development of chronic inflammatory diseases (39).

Experts recommend getting at least 150 minutes of moderately intense physical activity every week (40).

Examples of moderate-intensity exercise include brisk walking, water aerobics, dancing, housekeeping and gardening (41).

Get Adequate Sleep

Sleep plays a vital role in health, including the strengthening of your immune system (42).

A large body of research correlates sleeping under 6 hours per night with a host of chronic diseases, including heart disease, cancer and depression (43, 44).

In contrast, getting adequate sleep can protect you from illnesses, including the common cold.

One study noted that people who slept at least 8 hours per night were nearly three times less likely to develop a cold than those who slept fewer than 7 hours (45).

It’s generally recommended that adults aim for 7–9 hours of high-quality sleep every night for optimal health (46).

Reduce Stress

Your brain and immune system are tightly linked, and high levels of stress have negative effects on immunity.

Studies prove that chronic stress blunts your immune response and increases inflammation throughout your body, increasing your risk of infections and chronic conditions like heart disease and depression (47).

High levels of stress have also been linked to a greater chance of developing colds, so it’s worth practicing regular self-care to keep stress levels in check (48, 49).

Some ways to reduce stress include meditation, yoga and outdoor activities (50, 51, 52, 53).

Summary Emergen-C alone won’t give you a well-rounded immune system. You should also boost your immune system by maintaining good gut health, exercising regularly, getting adequate sleep and reducing stress.

Emergen-C is a supplement containing high doses of vitamins C, B6 and B12, plus other nutrients like zinc and vitamin D that are needed for immunity and energy levels.

Some evidence suggests that these nutrients can boost immunity in people with deficiency, but it’s unclear whether they benefit healthy adults.

Consuming Emergen-C in moderation is likely safe, but large doses of vitamin C, vitamin B6 and zinc can cause unpleasant side effects like stomach upset, nerve damage and copper deficiency.

In addition to proper nutrition, other ways to boost your immune system include maintaining good gut health, exercising regularly, getting adequate sleep and reducing stress levels.