Hypervitaminosis D: Vitamin D Overdose Symptoms and Risks

Author: BMJ
Published: 6 Jul 2022 - Updated: 6 Oct 2026
Publication Details: Peer-Reviewed | Case Study

Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content

Synopsis

This report, based on a peer-reviewed case study published in BMJ Case Reports, describes a middle-aged man admitted to the hospital after taking high doses of more than 20 over-the-counter supplements every day on the advice of a nutritional therapist. Blood tests showed very high calcium, a vitamin D level seven times above what is needed for sufficiency, and acute kidney injury. The treating doctors warn that hypervitaminosis D is a growing trend worldwide, with women, children and surgical patients most often affected, and that its symptoms - from vomiting, abdominal pain and increased thirst to confusion, abnormal heart rhythm and renal failure - stem largely from excess calcium in the blood. Because the account comes directly from the clinicians who managed the case, it serves as a reliable and practical warning for anyone who takes supplements regularly, including seniors and people with disabilities or chronic conditions who are often advised to take vitamin D for bone health and may be combining several products without medical oversight.*

At a Glance

1 - The man lost 28 lbs (12.7 kg) over nearly three months of symptoms.
2 - His symptoms began about one month after starting the regimen and continued after he stopped it.
3 - He spent eight days in the hospital receiving intravenous fluids and bisphosphonates to lower his blood calcium.
4 - Two months after discharge his calcium level had returned to normal, but his vitamin D level remained abnormally high.

Topic Definition

Hypervitaminosis D: Hypervitaminosis D, also known as vitamin D toxicity, is an uncommon but potentially serious condition in which too much vitamin D builds up in the body, almost always from taking high-dose supplements over time instead of from food or sunlight. The excess vitamin D causes the gut to absorb more calcium than the body can use, raising calcium in the blood to harmful levels - a state called hypercalcemia. That surplus calcium is responsible for most of the symptoms, which can include nausea, vomiting, excessive thirst, frequent urination, muscle weakness, confusion, kidney stones and kidney injury. Because vitamin D is cleared slowly, symptoms can persist for weeks or months after the supplements are stopped, and treatment focuses on halting intake and bringing calcium levels back down.

Overview

'Overdosing' on vitamin D supplements is both possible and harmful, warn doctors in the journal BMJ Case Reports after they treated a man who needed hospital admission for his excessive vitamin D intake. 'Hypervitaminosis D', as the condition is formally known, is on the rise and linked to a wide range of potentially serious health issues, they highlight.

The case concerns a middle-aged man who was referred to the hospital by his family doctor after complaining of recurrent vomiting, nausea, abdominal pain, leg cramps, tinnitus (ringing in the ear), dry mouth, increased thirst, diarrhea, and weight loss (28 lbs or 12.7 kg).

These symptoms had been going on for nearly three months and had started around one month after he began an intensive vitamin supplement regimen on the advice of a nutritional therapist.

The man had had various health issues, including tuberculosis, an inner ear tumor (left vestibular schwannoma), which had resulted in deafness in that ear, a build-up of fluid in the brain (hydrocephalus), bacterial meningitis, and chronic sinusitis.

He had been taking high doses of more than 20 over-the-counter supplements every day containing: vitamin D 150000 IU - the daily requirement is 10 mcg or 400 IU; vitamin K2 100 μg (daily requirement 100 - 300 μg); vitamin C, vitamin B9 (folate) 1000 μg (daily requirement 400 μg); vitamin B2 (riboflavin), vitamin B6, omega-3 2000 mg twice daily (daily requirement 200 - 500 mg), plus several other vitamin, mineral, nutrient, and probiotic supplements.

Once symptoms developed, he stopped taking his daily supplement cocktail, but his symptoms didn't go away.

The blood tests ordered by his family doctor revealed that he had very high calcium and slightly raised magnesium levels. And his vitamin D level was seven times over the level required for sufficiency.

The tests also indicated that his kidneys weren't working properly (acute kidney injury). The results of various x-rays and scans to check for cancer were normal.

The man stayed in the hospital for eight days. During that time, he was given intravenous fluids to flush out his system and treated with bisphosphonates - drugs normally used to strengthen bones or lower excessive calcium levels in the blood.

Two months after discharge from the hospital, his calcium level had returned to normal, but his vitamin D level was still abnormally high.

"Globally, there is a growing trend of hypervitaminosis D, a clinical condition characterized by elevated serum vitamin D3 levels," with women, children, and surgical patients most likely to be affected, write the authors.

Recommended vitamin D levels can be obtained from the diet (e.g., wild mushrooms, oily fish), exposure to sunlight, and supplements.

"Given its slow turnover (half-life of approximately two months), during which vitamin D toxicity develops, symptoms can last for several weeks," warn the authors.

The symptoms of hypervitaminosis D are many and varied, they point out, and are mostly caused by excess calcium in the blood. They include drowsiness, confusion, apathy, psychosis, depression, stupor, coma, anorexia, abdominal pain, vomiting, constipation, peptic ulcers, pancreatitis, high blood pressure, abnormal heart rhythm, and kidney abnormalities, including renal failure.

Other associated features, such as keratopathy (inflammatory eye disease), joint pain (arthralgia), and hearing loss or deafness, have also been reported, they add.

This is just one case, and while hypervitaminosis D is on the rise, it is still relatively uncommon, caution the authors.

Nevertheless, complementary therapy, including the use of dietary supplements, is popular, and people may not realize that it's possible to overdose on vitamin D or the potential consequences of doing so, they say.

"This case report further highlights the potential toxicity of supplements that are largely considered safe until taken in unsafe amounts or in unsafe combinations," they conclude.

Frequently Asked Questions

NOTE: Researched FAQs by Disabled World (DW)

How much vitamin D do adults need each day?

In the United States the recommended dietary allowance is 600 IU (15 mcg) per day for people aged 1 to 70 and 800 IU (20 mcg) per day for adults over 70. Infants up to 12 months need about 400 IU (10 mcg) daily.

How much vitamin D is too much per day?

The tolerable upper intake level set for adults and children aged 9 and older is 4,000 IU (100 mcg) per day from all sources combined. Higher doses are sometimes prescribed for a diagnosed deficiency, but they should only be taken for a limited time under medical supervision.

What blood level of vitamin D is considered toxic?

Vitamin D status is measured as 25-hydroxyvitamin D in the blood. Levels above 50 ng/mL (125 nmol/L) may be linked to adverse effects, and toxicity is typically seen at levels above 150 ng/mL (375 nmol/L), usually together with high blood calcium.

How is vitamin D toxicity diagnosed?

Doctors diagnose it with blood tests showing a high 25-hydroxyvitamin D level alongside raised calcium, often with a suppressed parathyroid hormone level. Kidney function tests, urine calcium and a full review of every supplement and medication being taken help confirm the cause.

Can vitamin D toxicity cause permanent damage?

Most people recover once the excess vitamin D clears, but prolonged high calcium can leave lasting harm. Possible long-term effects include kidney stones, calcium deposits in the kidneys and other soft tissues, and reduced kidney function.

Which medications can interact with high dose vitamin D?

Thiazide diuretics reduce the amount of calcium the kidneys remove, so combining them with high dose vitamin D raises the risk of high blood calcium. High calcium can also increase the chance of dangerous heart rhythm problems in people taking digoxin, and calcium supplements or antacids add to the total load.

Does taking vitamin K2 with vitamin D prevent toxicity?

There is no good evidence that vitamin K2 protects against vitamin D overdose. K2 is often marketed alongside vitamin D, but it does not stop excess vitamin D from raising blood calcium, and the only reliable protection is keeping the dose within recommended limits.

Can children and infants get vitamin D toxicity?

Yes, and they are more vulnerable because their safe upper limits are much lower - 1,000 IU per day up to 6 months, 1,500 IU from 7 to 12 months, 2,500 IU for ages 1 to 3, and 3,000 IU for ages 4 to 8. Most cases in infants result from dosing errors with concentrated liquid drops, so measuring carefully with the supplied dropper matters.

Insights, Analysis, and Developments

Editorial Note: Vitamin D is one of the most widely recommended supplements, which is partly why this case deserves attention - products sold without a prescription carry an assumption of safety that does not hold at very high doses or in untested combinations. Because vitamin D clears the body slowly, with a half-life of roughly two months, stopping the supplements does not bring quick relief, and this patient was still unwell weeks after abandoning his regimen. The authors are careful to point out that this is a single case and that toxicity remains relatively uncommon, so the lesson is not to avoid vitamin D but to treat it like any other active substance: know the dose on the label, add up what several products supply together, and tell a doctor or pharmacist about everything being taken, particularly when the advice to start came from outside conventional medical care.*

Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by BMJ and published on 6 Jul 2022, this content may have been edited for style, clarity, or brevity.

* Editorial additions by Ian C. Langtree.