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Hypervitaminosis D

Vitamin D toxicity

 

Hypervitaminosis D is a condition that occurs after taking very high doses of vitamin D.

Causes

 

The cause is excess intake of vitamin D. The doses need to be very high, far above what most health care providers normally prescribe.

There has been a lot of confusion about vitamin D supplementation. The recommended daily allowance (RDA) for vitamin D is 400 to 800 IU/day, according to age and pregnancy status. Higher doses may be needed for some people, such as those with vitamin D deficiency, hypoparathyroidism, and other conditions. However, most people do not need more than 2,000 IU of vitamin D a day. The doable upper level for vitamin D ranges from 25 to 100 mcg (1,000 to 4,000 IU), depending on age. Ask your provider what dose is best for you.

For most people, symptoms of vitamin D toxicity only occurs with vitamin D doses above 10,000 IU per day.

 

Symptoms

 

An excess of vitamin D can cause an abnormally high level of calcium in the blood (hypercalcemia). This can severely damage the kidneys, soft tissues, and bones over time.

The symptoms include:

  • Constipation
  • Decreased appetite (anorexia)
  • Dehydration
  • Fatigue and confusion
  • Frequent urination
  • Irritability
  • Muscle weakness
  • Vomiting
  • Excessive thirst (polydipsia)
  • High blood pressure
  • Passing large amounts of urine (polyuria)

 

Exams and Tests

 

Your provider will examine you and ask about your symptoms.

Tests that may be ordered include:

  • Calcium level in the blood
  • Calcium level in the urine
  • 25-hydroxy vitamin D level in the blood
  • 1,25-dihydroxy vitamin D level in the blood
  • Serum phosphorus level
  • X-ray of certain bones

 

Treatment

 

Your provider will likely tell you to stop taking vitamin D. In severe cases, other treatment may be needed.

 

Outlook (Prognosis)

 

Recovery is expected, but permanent kidney damage can occur.

 

Possible Complications

 

Health problems that can result from taking too much vitamin D over a long time include:

  • Dehydration
  • Hypercalcemia
  • Kidney damage
  • Kidney stones

 

When to Contact a Medical Professional

 

Contact your provider if:

  • You or your child shows symptoms of hypervitaminosis D and has been taking more vitamin D than the RDA
  • You or your child shows symptoms and has been taking a prescription or over-the-counter form of vitamin D

 

Prevention

 

To prevent this condition, pay careful attention to the correct vitamin D dose. Use vitamin D supplements from reliable licensed sources.

Many combination vitamin supplements contain vitamin D, so check the labels of all the supplements you are taking for vitamin D content.

 

 

Open References

References

Bilezikian JP, Walker MD, Binkley N, Goltzman D, Mannstadt M. Hormones and disorders of mineral metabolism. In: Melmed S, Auchus RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 27.

Greenbaum LA. Vitamin D deficiency (rickets) and excess. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 69.

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 199.

National Institutes of Health Office of Dietary Supplements website. Vitamin D fact sheet for health professionals. ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/. Updated June 27, 2025. Accessed November 3, 2025.

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          Review Date: 10/19/2025

          Reviewed By: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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