5 Signs You Are Getting Too Much Vitamin D

Vitamin D is essential for maintaining strong bones and supporting your overall health. However, too much can be harmful and cause symptoms like nausea, loss of appetite, confusion, and depression. While you don’t need to worry about getting too much from diet, vitamin D supplements can lead to excessive levels if consumed in excess for long periods.

1. Eevated Vitamin D Blood Levels

A healthcare provider can order a blood test to check your vitamin D level. High serum (blood) levels of vitamin D are defined as greater than 100 nanograms per milliliter (ng/mL), with adverse effects seen particularly at greater than 150 ng/mL.

Optimal blood vitamin D levels are generally between 30 ng/mL and 60 ng/mL. Experts do not believe that excessive sun exposure results in vitamin D toxicity due to how sunlight activates different forms of vitamin D in the skin.

Vitamin D toxicity is rare, and most cases of vitamin D toxicity are caused by inappropriate supplement dosing and prescription errors.

For example, a review of case reports of vitamin D toxicity found that many resulted in the overcorrection of vitamin D deficiency. In these cases, people presented with vitamin D levels well above optimal, ranging between 150 to 1,220 ng/mL.

It’s important to note that people with low vitamin D blood levels may need higher supplemental doses to meet and maintain an optimal vitamin D status. However, a healthcare provider should monitor this higher intake closely, checking blood vitamin D levels regularly.

Consult a healthcare provider before taking vitamin D supplements. They can help guide you on the appropriate dosage you should take.

2. Elevated Calcium Levels

One of the main roles of vitamin D is to increase calcium absorption in the gastrointestinal (GI) tract. Because of this, vitamin D toxicity also results in hypercalcemia (blood calcium levels above normal) and hypercalciuria (excess calcium in the urine).

If you have too much vitamin D in your blood, your blood calcium levels should also be assessed. Normal blood calcium levels are 8.4 to 10.2 milligrams per deciliter (mg/dL). Hypercalcemia is defined as blood calcium levels greater than 10.5 mg/dL.

Most of the symptoms seen with vitamin D toxicity are related to the associated hypercalcemia, which can be life-threatening.

These symptoms include:

In general, research shows that vitamin D-associated hypercalcemia only happens when extremely large doses of vitamin D, such as over 10,000 International Units (IU) per day, are taken over time.

Seek medical attention if you are experiencing symptoms related to vitamin D toxicity or hypercalcemia.

3. Gastrointestinal Symptoms

The most common side effects of too much vitamin D are related to hypercalcemia. This leads to GI-related symptoms, such as:

• Nausea
• Vomiting
• Loss of appetite
• Constipation

4. Altered Mental Status

Aside from the physical symptoms associated with too much vitamin D and related hypercalcemia, there may also be symptoms related to mental health. These include:

• Confusion
• Apathy (lack of interest, enthusiasm, or concern)
• Depression
• Irritability
• Hallucinations
• Psychosis
• Stupor (in extreme cases)

For example, one case study reported hypercalcemia in a 64-year-old person due to excess vitamin D supplementation of 200,000 IU daily. This resulted in altered mental status, along with other physical symptoms related to hypercalcemia.

The person was hospitalized and continued to be agitated and confused for 10 days, with blood calcium levels returning to normal after 18 days.

5. Kidney Complications

Too much vitamin D and the related hypercalcemia can lead to kidney complications, such as decreased kidney function, kidney injury, renal failure, and kidney stones. People with kidney disease also need to prevent taking too much vitamin D, as it can lead to serious kidney complications.

Numerous case studies have reported kidney complications related to excess vitamin D intake.

For example, a 65-year-old male took injections of 50,000 IU of vitamin D per week for one year. Upon admission to the hospital, he had acute (short-term) kidney injury, among other symptoms. Prompt treatment improved symptoms and avoided further damage to his kidneys.

Another case study involved a 54-year-old male who presented with a suspected kidney injury. Upon investigation, it was found that he was taking 8,000–12,000 IU of vitamin D drops daily for roughly 2.5 years.

Both his blood vitamin D and calcium levels were very high. After undergoing treatment for nearly one year, his calcium and vitamin D levels returned to normal. However, he was left with stage 3B chronic kidney disease.

How Much Vitamin D to Take Per Day

The recommended dietary allowance (RDA) for vitamin D for healthy people ages 1 to 70 years is 600 IU, or 15 micrograms (mcg), per day. It’s recommended for people over age 70 to get 800 IU, or 20 mcg daily.

This amount includes vitamin D you get from food, as well as dietary supplements.

Vitamin D is found naturally in a few foods, such as:

• Fatty fish (salmon, tuna trout)
• Beef liver
• Egg yolks
• Mushrooms treated with ultraviolet (UV) light

Vitamin D is added, or fortified, to some foods to increase intake in American diets. Commonly fortified foods include milk and breakfast cereals.

If your vitamin D levels are low, talk with a healthcare provider to determine how much vitamin D you should take to help bring it to optimal status.

Testing Vitamin D Levels 

Vitamin D status is tested by drawing blood to measure 25 hydroxyvitamin D, or 25(OH)D, in your blood. A healthcare technician or nurse will collect a small amount of blood from your arm into a test tube or vial using a small needle. The process usually takes less than five minutes.

The 25(OH)D level is the most accurate way to measure how much vitamin D is in the blood. It reflects vitamin D produced endogenously (inside the body) and obtained from diet and supplements.

Possible Vitamin D Side Effects

Generally, eating foods rich in vitamin D is well tolerated, and there are no known side effects from vitamin D produced by sunlight exposure. 

Supplemental vitamin D3 may cause some side effects, such as:

• Loss of appetite
• Weight loss
• Nausea
• Vomiting
• Constipation

Contact a healthcare provider if you experience these or any unusual symptoms while taking vitamin D supplements.