With the dietary supplement industry booming at over $60 billion, Americans have access to nearly 100,000 different products, from vitamins and minerals to herbal supplements promising weight loss, better immunity, and overall well-being. Nearly 75% of Americans take at least one supplement daily, but many mix multiple products—often without medical supervision—raising serious health risks.
The Risks of Supplement Stacking
The rise of supplement stacking—where people combine multiple supplements for enhanced effects—has become a popular trend, often promoted by influencers on social media. However, experts warn that taking multiple supplements can lead to dangerous interactions, overdosing, and serious health consequences like liver and kidney damage.
According to Dr. Mehrosh Naseem, a family medicine and integrative health physician at Ohio State University Wexner Medical Center, supplement stacking is akin to self-diagnosing without medical training.
“There can be interactions between supplements and between supplements and medications you may be taking. You can also take more than the maximum safe dose,” says Dr. Naseem. “It’s not safe to start taking supplements on your own without talking to a doctor.”
Liver and Kidney Damage from Supplements
A growing body of research highlights the dangers of unregulated supplement use:
- 20% of liver injuries in the U.S. are caused by herbal and dietary supplements.
- A 2022 study in Liver Transplantation found an eightfold increase in drug-induced liver failure from supplements between 1995 and 2020.
- A 2024 JAMA study revealed that 15 million Americans take supplements known to be toxic to the liver, including turmeric, ashwagandha, black cohosh, garcinia cambogia, green tea, and red yeast rice.
Are Supplements Safe?
While many people assume that supplements are inherently safe because they’re available over the counter, experts say that’s not always the case. “There is this perception that supplements are safer than medications, but they can have very powerful effects,” says Jessica Cording, a registered dietitian and author of The Little Book of Game-Changers.
Dietitian Laura Natali from NewYork-Presbyterian/Columbia University Irving Medical Center notes that while some supplements help fill nutritional gaps, others have unclear benefits and may even cause harm. “Many supplements promise solutions for common issues like fatigue or inflammation, but not all are backed by science,” she explains.
Supplements That Are Easy to Overdose On
Not all supplements carry the same risk. Vitamins fall into two categories:
- Water-soluble vitamins (like vitamin C and B vitamins): Excess amounts are flushed out through urine.
- Fat-soluble vitamins (like vitamins A, D, E, and K): Stored in body tissues, making overdose more likely.
According to Dr. Naseem, excessive intake of fat-soluble vitamins can reach toxic levels, causing nausea, headaches, and even life-threatening conditions.
Other minerals to be cautious with include:
- Magnesium: Too much can cause diarrhea.
- Calcium: Excess amounts can cause kidney damage.
- Iron: Overuse can lead to nausea, stomach pain, and toxic buildup in the liver and heart.
The Dangers of Herbal and Dietary Supplements
Unlike prescription medications, herbal supplements are not FDA-regulated before hitting the market. Dr. David Cutler, a family medicine physician at Providence Saint John’s Health Center, warns that many popular supplements—including turmeric, St. John’s wort, and ashwagandha—are linked to liver damage, especially when taken in high doses or combined with alcohol.
Cording adds that adaptogens like ashwagandha are often found in multiple supplements, functional beverages, and sleep aids, making it easy to unintentionally take excessive amounts.
How to Take Supplements Safely
Experts emphasize that while supplements can be beneficial, they should be taken cautiously and under professional guidance:
- Consult a healthcare provider before adding new supplements, especially if you take multiple products.
- Get a blood test to determine if you actually need a specific supplement and the appropriate dosage.
- Check for interactions with other supplements or medications you’re taking.
- Follow dosage instructions on labels and avoid excessive intake.
“Healthcare professionals have extensive training on this,” says Cording. “Unfortunately, the general public does not, which is why working with an expert is so important.”
Final Thoughts
While supplements can play a role in health and wellness, more is not always better. The lack of regulation in the supplement industry means consumers need to be extra cautious about what they take. Whether you’re looking for an immune booster, weight loss supplement, or energy enhancer, consulting with a healthcare provider first can prevent dangerous side effects and ensure you’re making the best choice for your health.
