Can vitamins and dietary supplements boost your immune system?
While using these products may seem beneficial, a VCU School of Pharmacy expert says you might be better off without them.
January 06, 2026
Studies show that around 23,000 emergency visits each year are linked to supplement use. (Getty Images)
By Mia Stephens
With winter in full effect, many people may lean on vitamins and dietary supplements to give their immune system a boost of protection.
However, nearly 23,000 emergency room visits each year are linked to supplement use.
“Vitamins and other supplements are often considered to be ’natural,’ but these products can cause side effects, interact with other medications or may be unsafe for people with certain medical conditions,” said Sarah Wheeler, Pharm.D., an assistant professor in the Department of Pharmacotherapy and Outcomes Science at Virginia Commonwealth University’s School of Pharmacy.
These products are not regulated by the U.S. Food and Drug Administration as a drug, meaning they don't go through the same testing as medicines before being sold in stores. So, it’s important to know how to pick the safest ones.
VCU Health News spoke with Wheeler to better understand how vitamins and supplements work and their health risks.
Do vitamins and dietary supplements help your immune system?
Vitamins and supplements do not offer equal benefits when avoiding an illness. For example, vitamin C could help prevent the common cold when used daily, but it's less likely to work if someone is already infected.
Other supplements like echinacea, zinc and elderberry have been shown to improve influenza (flu) symptoms or shorten the duration of symptoms if used within the first two days. On the other hand, oscillococcinum, which is marketed as a homeopathic flu and cold-relief medicine, has not shown enough current evidence to support its benefits.
Although certain vitamins and supplements may help prevent or treat infections during the cold and flu season, not all products are safe for everyone. The best course of action you can take is to stay up to date with your vaccines, avoid others when sick and maintain healthy habits.
Who is most likely to take vitamins and dietary supplements?
According to the Centers for Disease Control and Prevention, women are more likely than men to take vitamins and other supplements, and they use these products more as they get older.
Most people get enough vitamins and minerals from their regular diet because many foods are enriched with them. In some cases, people with certain medical conditions may need to take them routinely to avoid a vitamin deficiency.
In recent years, there’s been an increase in emergency visits related to supplement use. What is causing this?
With more people using these products, exposure to risks increases.
Studies show that some supplements have inaccurate doses that do not match the product’s label as well as unapproved ingredients, including prescription products that could cause significant harm.
Other contributing factors to the increase in emergency visits include accidental ingestion by children, side effects, allergic reactions and using a dose that was too high. Side effects for weight loss and energy products were linked to heart-related problems like palpitations, chest pain or racing heart.
If your household has children or pets, keep these products in a safe place that is out of reach to ensure they are not taken by mistake.
Do you have any tips for picking the best vitamins and dietary supplements?
When choosing supplements, my number one priority is safety. It is important to talk with your health care team, including a pharmacist, to identify supplements suitable for your health goals, have the most benefit and to catch any issues with your current regimen.
Most people get enough vitamins from their diet alone. However, if you choose to take a vitamin or other supplement, carefully review the ingredient list and label for any red flags. The Department of Defense has a free and easy-to-use checklist called the supplement safety scorecard, that can be used by anyone to identify safe products. Products that score less than 4 should be avoided.
Also, I highly recommend that you only use products that have been independently tested by trusted third parties, certified to contain the labeled ingredients and have a seal, indicating the quality and purity of the product.
What are the common side effects of taking too many vitamins and dietary supplements? At what point should you see a doctor?
Vitamin toxicity happens when someone consumes excessive amounts of vitamins that the body cannot process or release quickly.
The most common side effects are mostly gastrointestinal (GI)-related, including upset stomach, nausea, vomiting, diarrhea and cramping. They may also experience headaches, fatigue, dizziness and skin issues. If it’s not treated, vitamin toxicity can lead to organ damage.
If you are experiencing mild to moderate side effects after starting a new supplement, reach out to your primary care doctor.
For symptoms linked to taking a much higher dose than recommended, you should contact the Virginia Poison Center at VCU Health. Anyone experiencing severe symptoms, such as chest pain or trouble breathing, should seek emergency medical care immediately.
