DEBUNKED: What Immunity-Boosting Supplements Are Worth Your Time and Money?

It’s that time of year again: cold and flu season! But this time, add in a global pandemic. 

The good news is that the precautions you take against COVID-19–such as wearing a mask, social distancing, and washing your hands–are also the best way to protect yourself against a cold or flu. 

But, if you’re planning to give your immune system an extra boost, our pharmacists at Honeybee Health analyzed the efficacy of the most common immunity-boosting supplements in order to save you time and money. We also included a few additional tips from our pharmacists collected throughout their years of practice. 

DISCLAIMER: None of the supplements discussed in this article have been shown to be effective against preventing COVID-19. Also, none of the supplements will stop a cold or flu entirely and their respective impact depends on the individual. Should you decide to take a supplement, we recommend you take them preventively for the best results and discuss with your pharmacist beforehand. 


There are a lot of choices and a lot of opinions about what supplement works best. Ultimately, we suggest you stick to the options that have some evidence. No matter what you decide, discuss with your pharmacist to ensure you are taking the correct quantity and that there are no interactions with other medication(s). 

Deep Dive: The Most Common Supplement Options

Moderate Evidence

Studies showed the below supplements could (not “will”) have a positive effect in boosting your immune system.

Vitamin D:

Vitamin D is a hormone building block that helps strengthen the immune system. It is produced naturally in your skin when you are exposed to the sun and is often called the “sunshine” vitamin.  

Several studies have concluded that vitamin D may ward off colds and the flu. In 2017, the British Medical Journal published a meta-analysis–a review combining the results of multiple scientific studies–that showed taking vitamin D daily might help prevent respiratory infections, especially among patients who were already deficient in it. Meanwhile, a study released this September from the University of Chicago Medicine found that “vitamin D supplementation decreases other types of viral respiratory infection by 70% in people who are vitamin D deficient.”

Although both these studies note the effects were found primarily in vitamin D deficient individuals, an estimated 42% of the adult population is deficient, with higher percentages among those with darker skin. And in the wintertime–when people experience the cold or flu–is when many people have lower levels of vitamin D because of limited exposure to natural sunlight. Vitamin D is found in some foods such as fish and eggs, but to maintain proper levels of it during the fall and winter months, supplements are sometimes recommended. 

Before you rush to the store to buy vitamin D, a precaution: vitamin D has lately surged in popularity and there is some evidence to suggest people are over-consuming it. For most people, the recommended dose of vitamin D daily is 600 to 800 international units (IU). However, according to an analysis in The Journal of the American Medical Association (JAMA) of national survey data gathered between 1999 and 2014, there has been a 2.8% increase in the number of people taking more than 4,000 IU daily and an 18% increase in the number of people taking 1,000 IU or more daily. If you decide to take vitamin D during the colder months, consult with your pharmacist about the correct amount for you. 

  • Main drug interactions: Steroid medications, orlistat, cholestyramine, phenytoin, anti-tuberculosis drugs.
  • Suggested adult amount: 600-800 IU daily. 

Ginseng is a plant that has been used in traditional Chinese medicine for centuries. The most popular type of ginseng are American ginseng (Panax quinquefolium) and Asian ginseng (Panax ginseng), both of which have been studied for boosting your immune system.  

A recent meta-analysis reviewed nine different academic articles on ginseng’s efficacy and found there was some evidence of intervention when “administered in adjunct to influenza vaccination…as well as a significant reduction of their duration if only studies with healthy individuals were included in the analysis.” 

Ginseng is generally considered safe, but one study of Panax ginseng suggests the supplement’s benefits may attenuate with long-term use. 

  • Main drug interactions: Anticoagulant drugs, monoamine oxidase inhibitors, anti-diabetes medications. 
  • Suggested adult amount: 1-2 grams of raw ginseng root or 200-400 mg of extract daily. 

Zinc is a mineral in your body that helps support your metabolism and immune system. It can be found in foods such as meat and shellfish

Studies have shown that individuals deficient in zinc are more prone to respiratory infections and that taking zinc or zinc lozenges before a cold may inhibit replication of the virus. However, the studies compare different types and amounts of zinc, allowing some room for doubt. 

Zinc is one supplement that can cause a number of side effects, such as indigestion, nausea, vomiting, diarrhea, and more. High levels of zinc can result in “zinc toxicity” and copper deficiency. For these reasons, zinc is not recommended to consume on an ongoing basis. Should you take zinc, the National Institutes of Health recommends 40 mg as the upper limit dose for adults. 

  • Main drug interactions: Antibiotics, penicillamine, and diuretics.
  • Suggested adult amount: 40mg daily. 

Inconclusive Evidence

Studies showed evidence both for and against the below supplements’ abilities to boost your immune system.


Elderberry is a berry that comes from a tree and is edible once cooked. However, a specific elderberry product, Sambucol, is what we refer to when we specifically discuss how elderberries impact your ability to prevent a cold or flu. 

The studies on elderberries show conflicting evidence and consisted of small sample sizes. Although it is generally considered safe to consume, there is some thought that elderberry might result in an “an overzealous immune system response.”

Although specific elderberry products found in stores are considered safe in moderation, under no circumstances should you eat raw, wild elderberries. Also, because of the berry’s laxative effects, consumption may result in cramping. 

  • Main drug interactions: Immunosuppressants for rheumatoid arthritis or lupus, diuretics, laxatives.
  • Suggested adult amount: 1 tablespoon of an elderberry syrup extract four times daily.

Echinacea is an herbal supplement that is very commonly used during cold and flu season. Echinacea supplements can be made using different parts of the 10 species of the flowering herb–including the plant’s below-ground parts, above-ground parts, or both.  

All the differences within the supplements have made it more difficult to study its efficacy in preventing colds or the flu; there have been a handful of studies and taken all together, the results remain inconclusive. A 2013 Cochrane Review on Echinacea found there was no substantial benefit for preventing a cold or flu. A different study in 2010 published in the Annals of Internal Medicine also found that the benefits were too small to be considered statistically significant. Meanwhile, the director of preventative and alternative medicine at the University of Michigan said that echinacea might reduce a cold by 10 to 20%

Echinacea is considered safe for a short amount of time, but should not be taken if you have an autoimmune disorder like lupus, rheumatoid arthritis, or psoriasis. It may also not be safe if you have a plant allergy. 

  • Main drug interactions: Cytochrome P450 3A4 (CYP3A4) substrates, Cytochrome P450 1A2 (CYP1A2) substrates, immunosuppressants, caffeine, midazolam.
  • Suggested adult amount: 800-2400mg daily.

Garlic is an herb that belongs to the genus Allium. Consumed most frequently as a food, it is thought that garlic can provide additional health benefits in treating conditions related to the heart and blood system

It’s true that garlic has many health benefits–among them, that it may help your body absorb iron and zinc (which are important for immunity). But there are a limited number of studies that show garlic conclusively reduces symptoms of a cold or flu. 

Garlic is safe to consume, although in its raw form can cause bad breath, as well as possibly heartburn and other related stomach problems like gas. 

  • Main drug interactions: Isoniazid, HIV/AIDS medication, saquinavir.
  • Suggested adult amount: Dosage changes depending on intended use, check with your pharmacist. 
Vitamin C: 

Vitamin C is a water-soluble vitamin that is widely known for its variety of health benefits. These include preventing immune system deficiencies, eye disease, and even wrinkling. 

But, contrary to popular belief, whether or not vitamin C actually is a good option to fight against a cold or flu is controversial. In a 2013 study on the topic, the authors concluded that although there is insubstantial evidence, “it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them.”

Vitamin C is found in fruits (including oranges, lemons, strawberries, apples, cantaloupe, tomatoes) and vegetables (including peppers, broccoli, brussels sprouts, potatoes, cauliflower). Depending on your diet, you may already get the proper Recommended Dietary Allowance (RDA).

However, if you’d like to increase your vitamin C levels, supplements can be useful in getting your intake past the RDA. Although there’s been a debate in the scientific community around whether or not it’s superior to absorb vitamin C naturally (through food) or synthetically (through supplements), it’s now thought our body cannot distinguish between the two. 

Note that vitamin C is a safe supplement to take. Because it is water-soluble, it is absorbed quickly into the tissues of your body and extra amounts are excreted through urination. 

  • Main drug interactions: Antacids with aluminum, estrogens, fluphenazine, HIV/AIDS medication, statins. 
  • Suggested adult amount: 65-90 mg daily. 

No Substantial Evidence

Studies did not show the below supplement could boost your immune system.

Pelargonium sidoides:

Pelargonium sidoides is a plant often sold as a supplement by names like Umckaloabo and Zucol. 

A 2013 Cochrane Review found little evidence to show the supplement useful in preventing a cold or flu. Cochrane also noted that studies supporting pelargonium’s effectiveness were from “the same investigator (the manufacturer) and performed in the same region (Ukraine and Russia).” In addition to being unsubstiatied as a supplement, the safety of pelargonium is relatively unknown. 

  • Main drug interactions: None well documented. 
  • Suggested adult amount: Dosage changes depending on form, check with your pharmacist. 

Other Industry Tips

Over the years, our pharmacists have also seen a few products on the market that include a combination of different vitamins and minerals. One of the products patients have positively reacted to is Viracid by Ortho Molecular Products. Viracid includes zinc, vitamin A, vitamin C, and more. For immediate immune support, take 1-2 capsules per hour or as recommended by your health care professional. For immune maintenance, take 2 capsules per day or as recommended by your health care professional. Do not exceed 2 capsules every hour.

Another tip: think twice about taking Dayquil or Nightquil. They can come with side effects, including that they may have more medication than you need. 

And, don’t panic! The best thing you can do to prevent a cold or flu this season is to take the precautions already in place for COVID-19.

Jessica Nouhavandi