If you open your medicine cabinet, chances are there’s at least one dietary supplement in the mix. Supplements have become a staple in our wellness routines, especially among older adults aiming to fill nutritional gaps, boost energy and support their long-term health.
But while they can offer benefits when used correctly, taking too many supplements—or overdoing certain types—can lead to unwanted symptoms and potential health risks.
To learn more, we spoke with Kenny Mittelstadt, DACM, DC, LAc, DiplOM, a Functional Medicine Practitioner and Expert for Cielo. He breaks down the symptoms of taking too many supplements and how to manage them safely.
What we mean when we talk about supplements
When we talk about supplements, we’re referring to a wide range of products we take to support overall health, including single vitamins (like vitamin D or vitamin C), minerals (such as calcium and magnesium), herbal supplements and multivitamins. These products can help fill nutritional gaps, especially for essential nutrients like vitamin D, which many adults are deficient in. Most play a supportive role when used mindfully and according to medical advice.
Taking a doctor-recommended daily vitamin, such as vitamin D or a multivitamin, is generally safe and can be beneficial, especially if it’s filling a specific nutritional gap. However, overuse can become a concern if someone takes multiple supplements with overlapping nutrients, like a multivitamin plus additional high-dose vitamin D, calcium or iron supplements. If you take a daily vitamin, stick to recommended doses and consult your healthcare provider before taking any additional supplements to avoid overuse.
Symptoms of taking too many supplements
Taking multiple supplements or high doses of certain vitamins and minerals can cause various side effects, from subtle to disruptive. Below, Mittelstadt shares the most common symptoms:
Digestive issues
According to Mittelstadt, “the most common symptoms appear in the form of digestive discomfort since this is where most nutrients are absorbed.” Some of the first signs include nausea, bloating, cramping, constipation or diarrhea. This is particularly seen with those supplements containing magnesium, iron or vitamin C. Large amounts can overwhelm the digestive system, leading to frequent trips to the bathroom.
Skin reactions
“Itchiness, rashes or a flushing sensation,” can happen from taking high doses of certain supplements, he notes. B vitamins are more likely to cause immediate reactions, while fat-soluble vitamins (like vitamins A, D, E and K) are more likely to cause a delayed reaction of allergic contact dermatitis (ACD).
Cardiovascular symptoms
Mittelstadt says that “high blood pressure, irregular heartbeat or difficulty with blood clotting” can occur. When supplements disrupt the heart’s electrical signals, it can reduce blood supply to other organs and increase the risk of stroke or heart failure.
Neurological symptoms
“Drowsiness, irritability, brain fog, muscle weakness or visual changes” can also occur if you take too many supplements, he adds. High doses of calcium, iron and vitamin D, in particular, have been linked to muscle weakness, excessive fatigue and feelings of dizziness.
Urinary changes
Over-supplementation can also irritate the bladder. This includes an increased frequency of urination, changes in color, smell and texture (cloudiness) and even urinary incontinence from those supplements containing vitamin C or calcium.
Liver and kidney trouble
Supplements like vitamin A, green tea extract and some herbal supplements can stress the liver and kidneys, leading to symptoms like dark urine or yellowing of the skin and eyes (jaundice), which can indicate a more serious issue.
Which supplements are more likely to pose a risk?
Certain supplements are more likely to cause adverse effects when taken in excess.
“The fat-soluble vitamins (A, D, E, K) are four vitamins absorbed and stored in the body’s fat,” says Mittelstadt. “These vitamins can reach toxic levels if your intake and storage is too high. Excess vitamin A, for instance, can lead to liver damage and weaken bones, while too much vitamins E and K may impact blood clotting.”
Additionally, Mittelstadt says that “minerals are a nutrient category where overdosing can have serious consequences. Each mineral has a unique role, but they also interact with one another, creating a delicate balance that’s essential for optimal health.”
Herbal supplements can also pose risks at high doses. “Herbs like St. John’s Wort, ginseng and kava, for example, can lead to side effects ranging from digestive upset to nervous system overstimulation or liver strain, particularly when doses are too high or combined with certain medications,” says Mittelstadt.
Long-term risks of taking too many supplements
Chronic overuse of supplements can lead to serious, sometimes irreversible, health problems. Mittelstadt breaks down a few of these below:
- Organ strain: “The liver and kidneys, responsible for detoxifying the body, are particularly vulnerable to strain from high levels of fat-soluble vitamins and certain minerals. Excessive intake can burden these organs, potentially impairing their function.”
- Weakened bones: “Chronic overuse of vitamin A is linked to reduced bone density, increasing the risk of fractures over time.”
- Heart trouble: “High doses of calcium, especially when unbalanced with magnesium and vitamin K2, can contribute to arterial calcification and cardiovascular complications.”
- Neurological issues: “Vitamin D toxicity can lead to hypercalcemia (elevated blood calcium), which may impair cognitive function and mental clarity.”
- Masked deficiencies: “Excess folic acid (vitamin B9) can mask a vitamin B12 deficiency, potentially causing neurological issues like depression, anxiety, confusion and memory loss.”
How to safely take supplements: Follow the ‘Three Ts’
To make the most of supplements without risking your health, it’s important to follow a few best practices. Mittelstadt recommends following what he calls the “Three Ts”:
- Temporary: “Aside from a quality, bioavailable multivitamin or supplements for specific genetic needs, most supplements should be used temporarily,” says Mittelstadt. “Shifting away from the ‘medication for life’ mindset is essential. In general, supplements should help restore balance so that you can taper off as your health is restored.”
- Targeted: “Objective testing is invaluable to confirm if a supplement is truly needed,” notes Mittelstadt. “Avoid the ‘symptom-chasing’ approach of matching supplements to symptoms alone. Instead, use evidence-based guidance to ensure each supplement addresses a specific need based on blood work or genetic information.” For example, avoid taking multivitamins along with single high-dose vitamins.
- Therapeutic: “Work with a practitioner to determine proper dosages that have a therapeutic impact, ensuring supplements are effective. Regularly reassess your need for each one.” Avoid taking more than the daily recommended dose unless directed by a doctor.
Additionally, Mittelstadt encourages consulting with your doctor before adding supplements to your daily regimen, especially if you’re already on medication. “The interactions between medications and supplements, especially as combination products often contain overlapping ingredients…can increase the risk of excess intake,” he adds.
This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.
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