9 Vitamins and Supplements That Can Harm Your Liver or Kidneys
Vitamins and supplements can be useful in certain situations, but more isn’t always better. Some supplements can cause liver or kidney problems when taken in excessive amounts, combined with certain medications, or used in people who already have liver or kidney disease.
Here are nine supplements that deserve particular caution.
1. Vitamin A
Vitamin A is essential for vision, immunity, and normal growth. However, excessive amounts of preformed vitamin A can accumulate in the body and cause liver injury.
This is different from beta-carotene, which the body converts to vitamin A as needed.
2. Vitamin D
Vitamin D is important for calcium absorption and bone health. Extremely high doses over time can cause dangerously high calcium levels, potentially leading to kidney stones and kidney damage.
Taking more vitamin D than recommended doesn’t necessarily provide additional benefits.
3. Niacin (Vitamin B3)
High doses of niacin, particularly certain forms used to lower cholesterol, can cause liver injury.
Anyone taking high-dose niacin should do so under medical supervision.
4. Green Tea Extract
Drinking ordinary green tea is generally different from taking concentrated green tea extract.
Some concentrated extracts have been associated with liver injury, particularly at higher doses or in susceptible individuals.
5. Herbal Supplements With Kava
Kava has traditionally been used for relaxation and anxiety, but kava-containing products have been associated with serious liver injury in some people.
If you use a kava product and develop symptoms such as yellowing of the skin or eyes, dark urine, or unusual fatigue, seek medical attention promptly.
6. High-Dose Calcium
Calcium is essential for healthy bones and muscles, but excessive supplemental calcium can contribute to kidney stones in some people.
Whether you need a calcium supplement depends on your diet, age, medical history, and other factors.
7. Certain Herbal Weight-Loss Products
Some weight-loss supplements contain multiple concentrated ingredients, and their contents and doses can vary considerably.
Certain products have been associated with liver injury. The risk can be particularly difficult to assess when products contain numerous ingredients or don’t accurately reflect their contents.
8. Bodybuilding and Performance Supplements
Some bodybuilding products have been associated with liver injury, particularly products containing undeclared anabolic steroids or other drug-like ingredients.
Products marketed as “natural” aren’t automatically risk-free.
9. Iron Supplements
Iron is essential when you are deficient, but taking excessive amounts can be dangerous.
Large amounts of iron can cause serious toxicity and can damage organs, including the liver. Iron supplements should generally be taken when there is a specific reason for using them.
What Makes Supplements Risky?
The danger isn’t simply that a supplement is a “vitamin.” Risk can depend on:
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The dose
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How long you take it
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Your age and health
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Existing liver or kidney disease
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Other medications or supplements you’re taking
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Whether the product contains what its label claims
Signs You Shouldn’t Ignore
Possible signs of liver injury can include yellow skin or eyes, dark urine, unusual fatigue, nausea, vomiting, abdominal pain, or loss of appetite.
Kidney problems may cause changes in urination, swelling, nausea, fatigue, or pain, although kidney disease can also develop without obvious symptoms.
If you develop concerning symptoms after starting a supplement, stop and seek medical advice rather than trying to diagnose the problem yourself.
The Takeaway
Don’t assume that a vitamin or herbal supplement is automatically safe because it is sold without a prescription.
Before taking high-dose supplements—especially if you have liver or kidney disease or take prescription medications—talk with a doctor or pharmacist. The safest supplement is the one you actually need, at an appropriate dose.
