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Signs You've Taken Too Many Supplements, Say Doctors

Yes, you can have way too much of a good thing.
FACT CHECKED BY Emilia Paluszek

Over-the-counter supplements and vitamins are so often marketed as "all-natural", it's easy to fall into a false sense of security about dosage. "It doesn't make sense to me to take huge doses of vitamins and minerals unless there's a diagnosed problem, because there is so little evidence that they do good and sometimes a possibility that they might do harm," says Marion Nestle, MPH, PhD, professor of nutrition, food studies, and public health at New York University. Here are five signs you've taken too many supplements, according to doctors. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Vitamin D

Young Woman Taking Yellow Fish Oil Pill.

Be careful with how much vitamin D you take, as too much can cause serious harm. "Vitamin D toxicity, also called hypervitaminosis D, is a rare but potentially serious condition that occurs when you have excessive amounts of vitamin D in your body," says Katherine Zeratsky, RD, LD. "Vitamin D toxicity is usually caused by large doses of vitamin D supplements — not by diet or sun exposure. That's because your body regulates the amount of vitamin D produced by sun exposure, and even fortified foods don't contain large amounts of vitamin D. The main consequence of vitamin D toxicity is a buildup of calcium in your blood (hypercalcemia), which can cause nausea and vomiting, weakness, and frequent urination. Vitamin D toxicity might progress to bone pain and kidney problems, such as the formation of calcium stones."



Vitamin pills spilling from an open bottle

"Are you supplementing with zinc? Be careful! Excess zinc intake can lead to a copper deficiency which can cause neurological problems, including numbness and weakness in the arms and legs," says Barbara Broggelwirth, RDN, CDN. "Zinc is a trace mineral, meaning that we only need small amounts of it to support our health."


Vitamin C

woman taking vitamin D3

Too much vitamin C can cause gastrointestinal issues, experts warn. "Although too much dietary vitamin C is unlikely to be harmful, large doses of vitamin C supplements might cause: diarrhea, nausea, vomiting, heartburn, stomach (abdominal) cramps, and headache," says Katherine Zeratsky, RD, LD.




"Supplementation with beta-carotene, a compound that's converted to vitamin A by the body, was also shown to increase risk of death, especially for smokers or former smokers," says Donald Hensrud, MD. "Since vitamin A deficiency is rare in the US, it's probably not worth the potential risk to take this supplement."


Vitamin B-3

liver disease

Vitamin B-3 (niacin) can cause liver damage. "High doses can help lower high cholesterol levels, but this should be done only under the supervision of a doctor," says Dr. Hensrud. Side effects, including severe liver disease, can occur."

Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan