Can High Vitamin D Cause Nausea? Understanding Toxicity and Hypercalcemia

November 26, 2025 •

3 min read

While vitamin D deficiency is a widespread concern, research confirms that consuming very high doses from supplements can lead to a condition known as vitamin D toxicity. A prominent symptom of this serious issue is nausea, which arises from dangerously elevated calcium levels in the bloodstream.

Quick Summary

Excessive intake of vitamin D supplements can cause toxicity, resulting in high blood calcium levels (hypercalcemia). This condition can trigger gastrointestinal issues like nausea and vomiting, typically occurring with megadoses over a prolonged period.

Key Points

Nausea is a Symptom of Toxicity: High vitamin D intake can lead to nausea and vomiting, but only in cases of severe overdose and toxicity.
Hypercalcemia is the Cause: The nausea is not a direct effect of vitamin D but is caused by dangerously high blood calcium levels (hypercalcemia) triggered by the excess vitamin D.
Supplements are the Main Culprit: Vitamin D toxicity is almost always caused by taking extremely high doses of supplements for a prolonged period, not from sun exposure or diet.
Upper Limits Exist: The safe upper intake limit for adults is 4,000 IU per day, with toxicity often associated with doses significantly higher than this.
Other Symptoms Are Common: Alongside nausea, look out for other signs of vitamin D toxicity, including confusion, fatigue, and excessive urination.
Medical Attention is Necessary: If toxicity is suspected, immediate cessation of supplements and consultation with a healthcare professional is vital for proper treatment.

Yes, high doses of vitamin D can cause nausea. The discomfort isn't a direct result of the vitamin itself but is a secondary effect of hypercalcemia, a condition caused by excessive vitamin D intake. Vitamin D's primary function is to help the body absorb calcium, and when levels of the vitamin become toxic, the body absorbs an unhealthy amount of calcium. This hypercalcemia is what leads to many of the adverse side effects, including digestive issues like nausea, vomiting, and loss of appetite.

The Role of Hypercalcemia in Nausea

Hypercalcemia, or an abnormally high level of calcium in the blood, is the primary reason high vitamin D can cause nausea. Here’s how the process unfolds:

Excessive Absorption: When large amounts of supplemental vitamin D are consumed over a period of time, the body's ability to regulate calcium absorption is overwhelmed.
Calcium Buildup: As the gut absorbs more calcium, blood calcium levels rise to an unsafe level.
Systemic Effects: This excess calcium affects various systems in the body, including the gastrointestinal tract.
Digestive Distress: High calcium levels can interfere with normal digestive processes, leading to cramping, constipation, and symptoms of gastritis, which manifest as nausea and vomiting.

How Common is Vitamin D Toxicity?

Vitamin D toxicity (hypervitaminosis D) is a rare occurrence that almost exclusively results from consuming excessive amounts of supplements, not from diet or sun exposure. The skin naturally regulates vitamin D production from sunlight, and it's extremely difficult to get too much from fortified foods alone. Most reported cases involve prolonged intake of very large daily doses, often ten times or more than the recommended daily allowance (RDA). For adults, the safe upper limit (UL) is generally considered 4,000 IU (100 mcg) per day, though some studies suggest long-term intake near this level could still pose risks. Toxicity typically occurs when levels exceed 10,000 IU per day over many months.

Other Symptoms of Vitamin D Toxicity

Nausea is just one of several symptoms associated with vitamin D toxicity and resulting hypercalcemia. It is often accompanied by other signs that can be initially subtle but worsen over time.

Gastrointestinal Issues: Vomiting, loss of appetite (anorexia), constipation, or diarrhea.
Neurological Symptoms: Confusion, fatigue, muscle weakness, headaches, and in severe cases, stupor or coma.
Kidney Problems: Excessive thirst (polydipsia) and urination (polyuria), leading to dehydration. Prolonged toxicity can cause kidney stones and permanent kidney damage.
Cardiovascular Issues: High blood pressure and abnormal heart rhythms can occur in severe cases.

Treatment for High Vitamin D and Hypercalcemia

If vitamin D toxicity is diagnosed, treatment focuses on reducing calcium levels in the blood.

Discontinue Supplements: The first and most critical step is to stop all vitamin D and calcium supplementation immediately.
Increase Fluids: For mild cases, increasing fluid intake can help correct dehydration and aid the kidneys in flushing out excess calcium.
Medical Intervention: For moderate to severe cases, medical professionals may administer intravenous fluids (saline) and prescribe medications such as corticosteroids or bisphosphonates to block the release of calcium from bones.
Dietary Changes: Temporarily limiting dietary calcium intake is also recommended to help normalize blood calcium levels.

Comparison of Adequate vs. Toxic Vitamin D Intake


Feature	Adequate Vitamin D Intake (Adults)	Toxic Vitamin D Intake (Adults)
Daily Dosage (IU)	600-800 IU daily (RDA)	>4,000 IU, typically >10,000 IU daily over months
Primary Cause	Dietary sources, sun exposure, low-dose supplements	High-dose or mislabeled supplements
Blood Level (nmol/L)	50-125 nmol/L (20-50 ng/mL)	>150 nmol/L (150 ng/mL) or higher
Effects on Calcium	Promotes healthy calcium absorption and metabolism	Causes excessive calcium absorption, leading to hypercalcemia
Risk of Nausea	Virtually non-existent	A definite possibility, caused by elevated blood calcium
Other Symptoms	Generally none from intake	Vomiting, fatigue, confusion, kidney stones

Conclusion

In summary, high vitamin D can cause nausea, but only in cases of severe overdose leading to toxicity. This condition, known as hypervitaminosis D, causes a dangerous buildup of calcium in the blood (hypercalcemia), which disrupts normal body functions and triggers gastrointestinal distress. Toxicity is very rare and almost exclusively linked to long-term misuse of high-dose supplements, not from sun exposure or a healthy diet. If you experience persistent nausea or other concerning symptoms while taking vitamin D, it is crucial to consult a healthcare provider immediately for blood testing and appropriate medical guidance.

For more information on the recommended daily intake of Vitamin D and upper limits, you can visit the NIH Office of Dietary Supplements website.

Frequently Asked Questions

No, taking the recommended daily allowance (RDA) of vitamin D (600-800 IU for most adults) from supplements or food is unlikely to cause nausea. Nausea is a symptom of toxicity resulting from excessive intake, not normal use.

Nausea from high vitamin D typically occurs with megadoses over a prolonged period, often exceeding the safe upper limit of 4,000 IU/day. Many reported cases involve daily intake of 10,000 IU or more for months.

No, it is not possible to get vitamin D toxicity from sun exposure. The body naturally regulates its vitamin D production from sunlight, limiting the amount it produces.

Hypercalcemia is a condition of having too much calcium in the blood. When vitamin D levels are excessively high, it causes the body to absorb too much calcium, and this excess calcium can disrupt the normal functioning of the digestive system, leading to nausea and vomiting.

Other signs of vitamin D toxicity include vomiting, fatigue, muscle weakness, confusion, excessive thirst and urination, constipation, and in severe cases, kidney problems.

If you suspect you have vitamin D toxicity, stop taking all vitamin D supplements and see a healthcare provider immediately. They can perform blood tests to check your levels and recommend appropriate treatment.

Yes, some individuals, including those with certain underlying health conditions like sarcoidosis or hyperparathyroidism, can be more susceptible to the effects of high vitamin D and hypercalcemia.