Vitamin D Toxicity (Hypervitaminosis D)

What is vitamin D toxicity?

Vitamin D toxicity (hypervitaminosis D) happens when you have too much vitamin D in your body. It’s a rare complication that most often happens from taking higher-than-prescribed amounts of prescription vitamin D or too much of a self-prescribed over-the-counter (OTC) supplement.

Excess vitamin D leads to hypercalcemia (higher-than-normal levels of calcium in your blood), which is what causes symptoms.

Vitamin D toxicity usually isn’t life-threatening, but it can be quite harmful to your health. Severe cases can cause issues such as kidney failure, abnormal heart rhythm (arrhythmia), unsteady gait (ataxia) and confusion.

What is vitamin D?

Vitamin D is an essential vitamin — a hormone, really — that your body uses for normal bone development and maintenance. Vitamin D also plays a role in your nervous system, musculoskeletal system and immune system. Your body converts the vitamin D that you consume into the “active” form of vitamin D. The active form helps your body absorb calcium.

You can get vitamin D in a variety of ways, including:

• Sun exposure on your skin.
• Through the food and drinks you consume.
• Through nutritional supplements and prescription medications.

Vitamin D toxicity typically only happens from taking too much of a vitamin D supplement or prescription medication.

How common is vitamin D toxicity?

Vitamin D toxicity is rare. There are around 4,500 cases per year in the United States.

What is a toxic level of vitamin D?

The dose of vitamin D you need to take to produce toxic signs and symptoms varies greatly. It can occur with as little as 2,000 international units per day (IU/d) in susceptible people.

Healthy daily requirements for vitamin D include:

• People ages 19 to 50: 600 IU/d.
• People ages 50 to 70: At least 600 IU/d.
• People older than 70: At least 800 IU/d.

The maximum suggested daily requirement is 4,000 IU/d for healthy adults.

Talk to your healthcare provider if you’re concerned about your vitamin D intake. They can provide guidance on whether you should take a supplement and how much.

What are the symptoms of vitamin D toxicity?

The symptoms of vitamin D toxicity are mainly due to hypercalcemia. They include:

• Decrease in appetite.
• Nausea and vomiting.
• Constipation.
• Dehydration.
• Increased thirst (polydipsia).
• Frequent urination.
• Confusion, lethargy and fatigue.
• Muscle weakness and difficulty walking.
• Bone pain.
• Kidney stones.

What causes vitamin D toxicity?

Vitamin D toxicity most often results from taking too much prescription-strength vitamin D or too much of an over-the-counter vitamin D supplement. If you’re taking a vitamin D supplement, you should periodically get blood work to test your level of vitamin D.

Excessive sun exposure doesn’t cause vitamin D toxicity. Consuming too much vitamin D from your diet alone very rarely leads to vitamin D toxicity.

What are the risk factors for vitamin D toxicity?

People who take prescription-strength vitamin D are at risk for vitamin D toxicity due to the high dose of the medication unless they check their levels periodically. Certain conditions may require high doses of vitamin D, including:

• Vitamin D deficiency that doesn’t respond to a lower dose.
• Osteoporosis.
• Osteomalacia.
• Renal osteodystrophy.
• Psoriasis.
• Gastric bypass (weight loss) surgery.
• Celiac disease and other conditions that cause malabsorption of vitamin D.
• Inflammatory bowel disease (IBD).
• Multiple sclerosis (MS).

How is vitamin D toxicity diagnosed?

Healthcare providers rely on the following to diagnose vitamin D toxicity:

• Your symptoms.
• A history of your medications and supplements.
• Vitamin D blood tests.
• A calcium blood test.
• Kidney function tests.

How is vitamin D toxicity treated?

Treatment for vitamin D toxicity mainly involves lowering the level of calcium in your blood.

To do this, a healthcare provider will:

• Have you stop taking all vitamin D and calcium supplements until further notice.
• Give you IV fluids to treat dehydration.
• Give you corticosteroids and bisphosphonates (medications) in cases of severe toxicity to block bone resorption.

In rare cases, due to significant kidney damage, you may need hemodialysis to get rid of excessive calcium.

How can I prevent vitamin D toxicity?

There are some steps you can take to prevent vitamin D toxicity, including:

• Talk to your healthcare provider before starting a vitamin D supplement.
• Don’t take more vitamin D supplements than what your provider recommends.
• Don’t take more prescription vitamin D than what your provider prescribes.
• If you take prescription vitamin D, make sure you get regular blood tests to monitor the level of vitamin D in your blood.
• Store your vitamin D supplements and/or prescriptions in a safe place away from children and pets.

What is the prognosis for vitamin D toxicity?

The prognosis (outlook) for vitamin D toxicity is generally good with treatment. In most cases, people recover without any serious complications.

When should I see my healthcare provider about vitamin D toxicity?

If you’ve been taking a vitamin D supplement and you develop symptoms of vitamin D toxicity, such as persistent increased thirst, frequent urination and nausea and vomiting, see a healthcare provider as soon as possible.

If you take prescription vitamin D, be sure to see your provider regularly so they can monitor your levels of vitamin D.