How Do You Feel if You Have Too Much Vitamin D in Your Body?

November 18, 2025 •

3 min read

According to the National Institutes of Health, symptoms of vitamin D toxicity are most likely to appear when a person's daily intake is at least 10,000 IU. This can lead to a condition known as hypercalcemia, which is the main cause of the health problems you can experience if you have too much vitamin D in your body.

Quick Summary

An overdose of vitamin D, usually from supplements, can cause vitamin D toxicity, or hypervitaminosis D. This leads to hypercalcemia, an excessive buildup of calcium in the blood. Signs include digestive upset, fatigue, muscle weakness, confusion, and frequent urination. Severe cases may result in kidney damage and irregular heart rhythms.

Key Points

Hypercalcemia: Vitamin D toxicity causes dangerously high calcium levels in the blood, leading to most of the associated symptoms.
Source is Supplements: Toxicity nearly always results from taking excessive vitamin D supplements, not from sun exposure or diet alone.
Common Symptoms: Signs include nausea, vomiting, fatigue, muscle weakness, excessive thirst, and frequent urination.
Mental Effects: High calcium levels can also cause neurological symptoms like confusion, disorientation, irritability, and, in rare cases, coma.
Organ Damage: Untreated, long-term toxicity can cause kidney stones, permanent kidney damage, and heart rhythm abnormalities due to tissue calcification.
Treatment: Management involves immediately stopping supplementation, increasing hydration, and medical supervision to lower calcium levels and monitor organ function.
Prevention is Key: To prevent toxicity, always consult a healthcare provider before taking high-dose supplements and stay within recommended daily limits.

Understanding Vitamin D Toxicity and Hypercalcemia

Vitamin D is a crucial fat-soluble vitamin that helps your body absorb calcium and supports bone health, immune function, and more. While essential, consuming excessively high amounts of vitamin D through supplements can lead to a condition called hypervitaminosis D, or vitamin D toxicity. This is almost always caused by taking too much supplemental vitamin D, not from sun exposure or a typical diet. The primary consequence of vitamin D toxicity is hypercalcemia, which is a dangerously high level of calcium in the blood. It is this excess calcium that causes the body to feel unwell.

The Common Physical Symptoms of High Vitamin D

Excessive vitamin D intake typically results in high blood calcium levels, leading to a range of symptoms. These can include gastrointestinal issues such as nausea, vomiting, loss of appetite, stomach pain, or changes in bowel movements. Individuals may also experience fatigue, general weakness, and lethargy. Increased thirst and frequent urination are also common signs.

Neurological and Mental Effects of Excess Vitamin D

High calcium can affect mental and neurological function. This may manifest as confusion, disorientation, difficulty concentrating, irritability, nervousness, dizziness, or problems with balance and coordination. Severe cases can lead to more serious neurological impairment.

Comparing Vitamin D Toxicity vs. Deficiency Symptoms

Distinguishing between too much and too little vitamin D can be difficult due to some overlapping symptoms. The table below highlights key differences.


Symptom	Vitamin D Toxicity (Hypervitaminosis D)	Vitamin D Deficiency
Energy Level	Fatigue, lethargy, muscle weakness	Fatigue, general tiredness, low energy
Gastrointestinal	Nausea, vomiting, appetite loss, constipation	Often none, but severe deficiency may cause digestive issues
Thirst & Urination	Excessive thirst (polydipsia), frequent urination (polyuria)	Normal thirst and urination patterns
Mental State	Confusion, irritability, dizziness	Mood changes, depression, cognitive issues
Bones	Bone pain, loss of bone density	Bone pain, softening of bones (osteomalacia/rickets)

Long-Term Complications of Untreated Toxicity

Untreated vitamin D toxicity can lead to serious long-term health problems. The excess calcium can deposit in soft tissues and organs. This can result in kidney issues like kidney stones and potentially permanent kidney damage. High calcium levels can also impact heart function, potentially causing irregular rhythms and hardening of arteries. Paradoxically, prolonged excessive intake can also negatively affect bone strength.

When to Seek Medical Attention

It is advisable to consult a healthcare provider if you experience symptoms suggestive of vitamin D toxicity, particularly if taking supplements. Diagnosis typically involves medical history and blood tests. Treatment focuses on lowering calcium levels, which usually means stopping supplements and increasing fluid intake; medication may be necessary in severe cases. With timely intervention, most individuals recover without major lasting issues. Always check with your doctor and consult reliable sources like the NIH for safe intake guidelines.

Conclusion

Feeling unwell due to excess vitamin D is generally linked to hypercalcemia caused by over-supplementation. Symptoms range from digestive and fatigue issues to potential neurological effects and, if untreated, serious organ damage. Prompt identification of symptoms and medical consultation are vital for recovery. Responsible supplementation under medical guidance is essential to prevent toxicity.

Frequently Asked Questions

The main reason you feel unwell is because an excessive intake of vitamin D causes a buildup of calcium in your blood, a condition known as hypercalcemia.

No, it is nearly impossible to get too much vitamin D from sun exposure, as your skin naturally regulates the amount it produces. You also cannot achieve toxic levels from food alone. Toxicity is almost always caused by taking too many supplements.

Early symptoms often include digestive issues like loss of appetite, nausea, and vomiting, followed by fatigue, weakness, excessive thirst, and frequent urination.

Excess calcium from vitamin D toxicity can lead to the formation of kidney stones. Over time, it can cause kidney damage and, in severe cases, permanent kidney failure.

Since vitamin D is fat-soluble and can be stored in the body, it may take weeks or even months for levels to return to a safe range, depending on the severity of the toxicity.

The first step is to immediately stop taking all vitamin D and calcium supplements. A healthcare provider will then focus on managing the symptoms and lowering blood calcium levels.

Long-term, untreated toxicity can lead to permanent kidney damage, irregular heart rhythms, and a paradoxical weakening of bones due to calcium imbalance.