Although most people take vitamin D supplements without any problems, it’s possible to take too much. This is called vitamin D toxicity. Vitamin D toxicity, where vitamin D can be harmful, usually happens if you take 40,000 IU per day for a couple of months or longer, or take a very large one-time dose. Vitamin D is fat-soluble, which means your body has a hard time getting rid of it if you take too much. When you take large amounts of vitamin D, your liver produces too much of a chemical called 25(OH)D. When your 25(OH)D levels are too high, this can cause high levels of calcium to develop in your blood. High blood calcium is a condition called hypercalcemia. The symptoms of hypercalcemia include: In some rare diseases, you may be at risk of hypercalcemia even if you have low vitamin D levels and haven’t taken much vitamin D. These diseases include primary hyperparathyroidism, sarcoidosis and a few other rare diseases. See our Hypersensitivity page page for more information.
A blood test to measure your 25(OH)D levels can tell you whether you have too high of vitamin D levels. If your 25(OH)D levels are above 150 ng/ml this is considered potentially toxic and potentially harmful to your health. You know if your 25(OH)D levels are toxic by a blood test to measure calcium. If calcium is high and 25(OH)D is high, then you are getting too much vitamin D. Very high levels of 25(OH)D can develop if you: If you have taken this much vitamin D, seek medical attention. Your health providers will get your calcium and 25(OH)D levels tested. The current recommended daily allowances for vitamin D set by the Food and Nutrition Board are conservative, so you don’t need to feel worried about toxicity if you take more than their recommended daily allowance. You can find out more about daily vitamin D supplementation on our page, How do I get the vitamin D my body needs? Have you taken more than 300,000 IU in the past 24 hours OR have you been taking more than 10,000 IU/day for the past three months or longer?
The more you weigh, the more vitamin D your body can handle; the less you weigh, the less vitamin D your body can handle. The above cutoffs of 300,000 IU in 24 hours or more than 10,000 IU/day for three or more months apply to average adult weight (125-200 lbs). So, how do you know if your child has gotten too much vitamin D? For children that weigh 25 lbs or less, more than 50,000 IU in 24 hours or 2,000 IU/day for over three months is too much and potentially toxic. For children that weigh between 25 and 50 lbs, more than 100,000 IU in 24 hours or 4,000 IU/day for over three months is too much and potentially toxic. For children that weigh between 50 and 75 lbs, more than 150,000 IU in 24 hours or 6,000 IU/day for over three months is too much and potentially toxic. For children that weigh between 75 lbs and 100 lbs, more than 200,000 IU in 24 hours or 8,000 IU/day for over three months is too much and potentially toxic. If your child has taken too much vitamin D, seek medical attention.
If your level is greater than 150 ng/ml, this is considered too high and potentially toxic. Seek medical attention if you have symptoms of hypercalcemia (listed above). If you do not have symptoms, consider lowering your level. Please see our pages on 25(OH)D reference ranges and our page on how to get the right amount of vitamin D: If your level is not greater than 150 ng/ml, then you are not potentially toxic in vitamin D. Please read our pages on vitamin D levels and how to interpret your results:A small study suggests that very high doses of vitamin D taken each week may help ease muscle and joint pain associated with taking an aromatase inhibitor as part of the treatment plan for hormone-receptor-positive breast cancer. These results were presented at the 2009 San Antonio Breast Cancer Symposium.Hormonal therapy medicines -- either an aromatase inhibitor or tamoxifen -- are commonly prescribed after surgery for early-stage, hormone-receptor-positive breast cancer in postmenopausal women to lower the risk of the cancer coming back (recurrence).
Hormonal therapy medicines are also sometimes used to treat advanced-stage, hormone-receptor-positive breast cancer.Muscle and joint pain are common side effects of the aromatase inhibitors Arimidex (chemical name: anastrozole), Aromasin (chemical name: exemestane), and Femara (chemical name: letrozole). For some women this pain can be severe. Doctors aren't sure why aromatase inhibitors cause muscle and joint pain. Aromatase inhibitors work by lowering the amount of estrogen in the body -- this estrogen decrease is probably part of the cause of these side effects. Lower estrogen levels also can cause weakened bones while you're taking an aromatase inhibitor.In this small study, 60 postmenopausal women diagnosed with hormone-receptor-positive breast cancer that wasn't metastatic were treated with Arimidex for at least 8 weeks after surgery. All the women had muscle and bone pain that began after they started taking Arimidex. All the women took over-the-counter supplements of calcium (1,000 mg) and vitamin D3 (400 IU) each day.
The women were split into two groups:Women with kidney problems or other medical conditions that could be made worse by high doses of vitamin D weren't allowed in this study.The doctors used several tools to rate the women's pain at the start of the study and then 2, 4, and 6 months later:A spine and leg bone mineral density test, which evaluates the health of bones, was done when the study started and 6 months later.After 2 months, women who got high doses of vitamin D weekly had notably less muscle and joint pain and were better at walking and climbing stairs compared to women who got the placebo. But after 4 and 6 months, when the women got high doses of vitamin D monthly instead of weekly, the improvements in pain and movement they had at 2 months went away.Women who got high doses of vitamin D tended to maintain bone health (as measured by the bone mineral density test) better than women who got the placebo.Two women developed high calcium levels in their urine and stopped taking the high doses of vitamin D;
other than that, the high doses of vitamin D didn't cause any side effects.The researchers aren't sure how high doses of vitamin D each week helps ease muscle and joint pain that can be caused by Arimidex.High doses of vitamin D can be safe as long as you are closely monitored by a doctor. Too much vitamin D can cause dangerously high calcium levels in your blood and urine, kidney stones, and kidney damage. While the results of this study seem promising, more research is needed to better understand the benefits and risks of high doses of vitamin D, especially over longer periods of time. Researchers also need to study which form of vitamin D is best for this type of treatment.If you're a postmenopausal woman taking an aromatase inhibitor as part of your treatment for hormone-receptor-positive breast cancer, you might be having muscle and joint pain. If these side effects are a problem, talk to your doctor about how to manage them. You might be able to switch to a different medicine. Don't start taking high doses of vitamin D on your own.