Vitamin D is generally considered to be a very safe and beneficial supplement to take, especially because a high percentage of people are deficient in this important vitamin. While there’s good reason to prioritize getting enough vitamin D — considering vitamin D deficiency symptoms can impact the immune system, heart and more— it’s still potentially possible to get too much vitamin D.
How much is too much vitamin D? “Vitamin D toxicity” can occur when taking high doses upward of 10,000 to 40,000 international units (IU) per day for several months or longer.
As covered more below, signs of too much vitamin D can include frequent sickness, fatigue, weakness, digestive issues and muscle/bone pain.
Symptoms of Too Much Vitamin D
We need enough vitamin D in order for our bodies to function properly because vitamin D has many roles, including helping with absorption and regulation of minerals like calcium, magnesium and phosphate; bone health; immune function; growth and development in infants/children; cellular renewal; cognitive health; and nerve function.
In a perfect world, we would all get enough vitamin D from the single best natural source there is: sun exposure. However, we know that today most people don’t spend enough time in the sun.
Therefore, supplements have become widely recommended and popular.
Signs of Too Much Vitamin D
You’re most likely to experience symptoms of too much vitamin D when taking supplements in high doses for a long period of time. Some signs that you may be supplementing with more vitamin D than necessary include:
- Getting sick more often
- Abdominal pain and digestive issues, like nausea, constipation, diarrhea or loss of appetite
- Increased thirst and dry mouth
- Urinating frequently
- Muscle weakness or pain
- Bone pain
- Brain fog, feeling confused and dizziness
- Irregular heartbeat
- Chest pains
- Changes in blood pressure
Can too much vitamin D cause anxiety? Because vitamin D toxicity can cause side effects like rapid heartbeat, confusion, restlessness and chest pains, it can potentially cause feelings associated with anxiety.
Having abnormally high levels of vitamin D (also referred to as vitamin D intoxication or hypervitaminosis) typically occurs from supplementing rather than due to sun exposure or dietary intake.
The reason that taking high doses of vitamin D can be problematic is because vitamin D (along with vitamins A, E and K) is a fat-soluble vitamin. This means it’s stored in body fat and can remain in your body for a long time.
While there’s yet to be an agreed upon daily requirement for vitamin D, health experts agree that many people can benefit from supplementing with vitamin D (particularly vitamin D3), including adults, children and infants.
The standard recommendation in terms of vitamin D intake to prevent deficiency, according to the USDA, is between 600 to 800 IU per day for adults and 400 IU for children. However, some feel that this number should be higher, such as around 2,ooo to 5,000 IU per day.
The amount of vitamin D that you need daily depends on a number of factors, such as your body weight, age, sex and medical history. As a general recommendation, aim for these amounts of vitamin D3 in supplement form:
- Children younger than 5: 35 units per pound/day
- Children ages 5–10: 2,500 units/day
- Adults/pregnant women/breastfeeding women: about 5,000 units/day
Toxicity vs. Deficiency
Taking high doses of vitamin D causes your liver to produce a chemical called 25(OH)D, which makes calcium accumulate in your bloodstream (called hypercalcemia).
In rare cases this can result in kidney damage and calcium deposits forming in the kidneys (called nephrocalcinosis). This is a serious condition that causes symptoms like nausea, dehydration, fever and pain.
25(OH)D can be measured via a blood test. A level of 25(OH)D in the blood that is higher than 150 ng/ml is considered potentially toxic.
While it’s rare, several other conditions aside from hypercalcemia can occur if someone experiences vitamin D toxicity, such as hyperparathyroidism, sarcoidosis and a few other rare diseases.
If you notice signs of vitamin D side effects and you’re at risk for experiencing vitamin D toxicity — due to taking more than 300,000 IU in the past 24 hours or more than 10,000 IU per day for the past several months — then stop taking vitamin D, and visit your doctor right away for a blood test. Your doctor will test you for hypercalcemia and also discuss any symptoms you’re having.
While taking too much vitamin D can be dangerous in some instances, keep in mind that getting too little vitamin D and experiencing a deficiency are also problematic.
Your goal should be is to strike a balance and get the amount of vitamin D your body needs without taking excessive quantities
Is it safe to take 5,000 IU of vitamin D3 daily? If not, then how much vitamin D3 is safe?
There is little risk associated with taking around 5,000 IU of vitamin D3 daily, but some people may do best with a higher or lower amount.
What’s considered “enough vitamin D”? Most experts believe vitamin D levels should be above 20 nanograms (ng) per milliliter (mL) of blood to prevent deficiency.
On the other hand, vitamin D toxicity (too much vitamin D in the blood) is considered anything above 200–240 ng/mL of blood.
Can you take too much vitamin D if you know that you’re already deficient?
If a vitamin D blood test reveals that you’re low in vitamin D, you can either take smaller doses for a long period of time to bring your level up, such as 5,000 IU per day, or a high dose administered over the course of several weeks. If you take a very high dose all at once, such as more than 40,000 IU, then it’s possible that side effects may occur.
How to Treat/Prevent It
The best way to avoid experiencing vitamin D toxicity is to not take very high doses of vitamin D in supplement form, such as 10,000 IU per day for more than several days in a row.
Vitamin D toxicity is most likely to occur when taking high doses of supplements for a couple of months or longer, such as 40,000 IU or more. It may also potentially occur from taking a very high dose only one time, such as more than 300,000 IU in a 24-hour period.
These amounts apply to “average weight adults” who are around 125–200 pounds but are not applicable to children or those who weigh much less. For children that weigh between 25 and 75 pounds, more than 50,000 IU in 24 hours or 2,000 to 6,000 IU/day for over three months may be too much and potentially cause vitamin D toxicity.
If it’s determined that your blood level is too high, how do you get rid of excess vitamin D?
If you need to flush vitamin D out of your system, your doctor might recommend vitamin D toxicity treatments including stopping vitamin D intake, restricting dietary calcium and receiving intravenous fluids and/or medications, such as corticosteroids or bisphosphonates, to control symptoms.
What’s the best way to maintain a normal level?
Ideally you want to maintain normal vitamin D levels without supplements by getting enough sun exposure or by taking supplements in a dose that is considered safe (between 1,500–5,000 IU for most adults).
Spending time in the sun with your skin exposed for about 15–20 minutes most days, without sunscreen, is your surest way to get enough vitamin D.
Eating vitamin D-rich foods — such as fish and other seafood, eggs, and raw milk — can also help improve your vitamin D level. Sunshine and vitamin D foods will not cause vitamin D toxicity because your body regulates how much vitamin D is made/absorbed by these sources.
Who should avoid taking vitamin D supplements?
Because vitamin D can interact with some medications, vitamin D supplements should not be taken by anyone who takes these prescription drugs:
- Epilepsy drugs, such as phenobarbital and phenytoin
- The weight loss medication called Orlistat
People who have any of the health conditions listed below should not supplement with vitamin D without being monitored by a doctor:
- Kidney disease
- Liver disease
- Primary hyperthyroidism
- Granulomatous tuberculosis
- Metastatic bone disease
- Williams syndrome
- Many people take vitamin D supplements to avoid deficiency, however it’s possible to take too much and then develop side effects.
- To be safe, avoid taking high doses (such as 40,000 IU or more per day) for a long period of time, such as more than several months, unless working with a doctor.
- Toxicity may also potentially occur from taking a very high dose only one time, such as more than 300,000 IU in a 24-hour period.
- The standard recommendation in terms of vitamin D intake to prevent deficiency is between 600 to 800 IU per day for adults. If you feel you might benefit from more, ask your doctor for her or his recommendation.