Calcium overdose: what you should be aware of

Calcium Überdosierung: Was du beachten solltest

From an early age we are told that we should drink milk to get strong bones. The mineral calcium it contains is what is responsible for bone formation, among other things. And while calcium intake is always advised, it's possible to get too much and develop a calcium overdose.

An overdose of calcium can have serious health consequences. In this article, we explain how calcium works in our body and what you should consider when taking calcium. We also inform you what hypercalcemia is, how it is caused and what you can do about it.

the essentials in brief

  • Calcium is a vital mineral that we need, among other things, for our bone structure, blood clotting and cell structure. If you have a calcium overdose, you have too much calcium in your blood. This elevated calcium level is called hypercalcemia.
  • Hypercalcemia can have a variety of causes. Illnesses, medication and food can cause an increased calcium value. Dietary supplements in particular carry a high risk of overdosing on the mineral.
  • To counteract a calcium overdose, a low-calcium diet and plenty of water is sufficient if you are symptom-free. If the calcium level is very high, phosphates or other medications can help. In the event of a hypercalcemic crisis, hospitalization is necessary.

Calcium Overdose: What You Should Know

In the following we have put together the most important information about the mineral calcium and its dosage. With this you will know how an overdose occurs, what the symptoms are and how to deal with them.

First of all: This page is only intended for informative purposes and should not be used as a basis for self-diagnosis. If you suspect that you are suffering from a calcium overdose, please discuss this with your doctor.

Role of calcium in the body?

Calcium is an essential mineral that is responsible for many functions in our body. It is responsible for strengthening and maintaining bones and teeth, for blood clotting and the transmission of stimuli in nerve cells. In addition, it is involved in cell stabilization and division and the contraction of muscles. It also contributes to the normal functioning of energy metabolism and digestion.(1)

Since our body cannot produce calcium itself, we have to get it from food. Calcium-rich foods include:

  • Dairy products
  • Green vegetables
  • nuts
  • Whole grain bread
  • Muesli
  • Mineral water
  • soy milk

Products made from cow's milk are particularly rich in calcium. In fact, you only need a handful of dairy products to meet your daily needs.

mug of milk

Milk contains a lot of calcium, but it is not necessarily healthy. (Image source: Engin Akyurt / Pixabay)

In order for calcium to be able to carry out its functions in the body, an adequate supply of vitamin D must be ensured at the same time. Vitamin D ensures the absorption of calcium from the gastrointestinal tract into the blood and promotes its feeding into the bones. (1)

What is the daily calcium requirement?

The DGE (German Society for Nutrition eV), an independent scientific society, specifies the amounts of essential vitamins and minerals that should be consumed in order to ensure normal bodily function. On the subject of calcium, they have published the following estimates for an adequate daily intake: (2)

Old Calcium in mg per day
Infants (0 to 4 months) 220 mg
Infants (4 to 12 months) 330 mg
Children (1 to 4 years) 600 mg
Children (4 to 7 years) 750 mg
Children (7 to 10 years) 900 mg
Children (10 to 13 years) 1100 mg
Youth (13 to 19 years) 1200 mg
Adults (19 to 65 years and older) 1000 mg
pregnant women 1000 mg
breastfeeding 1000 mg

From these values ​​it can be seen that the calcium requirement does not correspond to the general knowledge of most people that a particularly large amount of calcium is needed for bone formation at a young age. In fact, the highest need is between the ages of 13 and 19.

Can too much calcium damage the body?

As with many other things, calcium dosage is important. If you have an adequate amount of calcium, the body works, with too little or too much it can sometimes lead to health problems. With normal health and adequate intake of calcium, the blood calcium level should be within the guideline values. The concentration of calcium is measured in millimoles.

Old Normal value for calcium in mmol/l
newborn 1.75 - 2.70 mmol/l
infants and children 2.05 - 2.70 mmol/l
Adult 2.2 - 2.65 mmol/l

In newborns, the calcium level in the blood should be between 1.75 and 2.70 mmol/l. Infants and children should have a value between 2.05 and 2.70 mmol/l. In adults, the calcium value should be between 2.2 and 2.65 mmol/l.(9)

If the calcium value is lower than the normal values, there is a calcium deficiency . When the calcium level in the blood is high, it is called hypercalcemia. If the value is higher than 3.5 mmol/l, a hypercalcemic crisis can occur. In the worst case, this can be life-threatening. (4)

Elevated calcium levels over the long term can promote the deposition of calcium phosphate in vessels, which could increase the risk of cardiovascular disease and cardiovascular infarction. In addition, deposits can form in the kidneys and urinary tract, which can lead to impaired kidney function.

Taking calcium supplements was classified as particularly dangerous. Studies have shown that just 1 gram of calcium in tablet form daily increases the risk of suffering a heart attack or stroke. (10)

What causes a too high calcium value?

If the calcium level in the blood is higher than normal, an overdose can occur. This so-called hypercalcemia can have various causes. For a simple overview, we have compiled the most common causes of a calcium overdose in the following table:

Caused Explanation
pre-existing conditions and heredity Certain diseases and heredity can lead to increased calcium levels in the blood.
confinement to bed If you stay in bed for a long time, calcium can be released into the blood due to the high rate of bone breakdown.
Certain medications Some medications can promote hypercalcemia.
calcium supplements Calcium preparations often contain many times the daily requirement.
Other supplements Overdose of vitamin A and vitamin D supplements can cause hypercalcemia.
Groceries A diet with excessive consumption of foods containing calcium can, in rare cases, lead to an overdose.

There are a number of pre-existing conditions and heredity that can lead to an overdose of calcium. Pre-existing conditions include, for example, an overactive thyroid gland, underactive adrenal cortex, excess protein in the blood, excessive production of growth hormones, malignant tumors or chronic diseases. Hereditary causes of a calcium overdose can be, for example, a disturbance in calcium excretion or a deficiency in the enzyme phosphatase. (8th)

Some medications can also cause hypercalcemia. For example, they can lead to the dissipation of calcium or promote bone loss.

You should always read the package insert for medication to be informed about possible effects on your calcium level.

Being bedridden for a longer period of time inevitably leads to severe bone deterioration because they are not moved. This bone breakdown then releases the calcium from the bones into the blood and can thus cause hypercalcemia.

Overdosing on vitamin A or vitamin D supplements can also lead to an excessive increase in calcium levels. An excess of vitamin D ensures increased absorption of calcium from food and increased leaching of calcium from the bones. (6) Excessive intake of vitamin A can lead to reduced bone density and associated skeletal damage. (7)

calcium supplements

Calcium supplements can quickly lead to an overdose of calcium. (Image Source: Sharon McCutcheon / Unsplash)

Irrespective of previous illnesses, calcium supplements are probably the most common cause of hypercalcaemia. Many supplements are dosed higher than the daily requirement intake published by the DGE suggests. Since dietary supplements are taken in addition to food, a calcium-rich diet can further increase calcium levels.

In rare cases, the consumption of calcium-rich foods alone is responsible for an overdose. So with a balanced diet, hypercalcaemia is unlikely to be caused by your eating habits. (5)

What are the symptoms of a calcium overdose?

A slightly elevated calcium level does not usually cause any symptoms. However, if the value is higher, the following symptoms can occur, for example (3):

  • Headache
  • tiredness and lack of concentration
  • depressions
  • digestive problems
  • nausea and vomiting
  • Kidney damage and kidney stones
  • muscle pain and muscle weakness
  • cardiac arrhythmias

In a hypercalcemic crisis, the following symptoms appear within a short period of time:

  • increased urination
  • abnormally increased thirst
  • fever and vomiting
  • dehydration
  • disturbances of consciousness up to coma

If you experience these symptoms, you should urgently go to a hospital, as in the worst case it can lead to cardiac arrest. (4)

How can you lower the calcium level in the blood?

We have already been able to explain to you in detail that an increased calcium value is not healthy. Below we will explain how to get rid of hypercalcemia and what you can do to prevent calcium overdose.

If a medical condition is responsible for the hypercalcemia, it must be treated to permanently lower calcium levels as well. In the case of a hereditary disease, the calcium level must be controlled with medication. If calcium, vitamin A or D supplements are responsible for the calcium overdose, they should be discontinued.

If the symptoms of mild to moderate hypercalcemia are severe, phosphates can trigger diarrhea, which flushes excess calcium out of the intestinal tract. (11)

If it is just mild hypercalcemia without symptoms, drinking plenty of fluids and eating a low-calcium diet is enough to get the calcium level under control again.

To prevent calcium overdose, you should always drink enough water so that calcium is metabolized well. You should also make sure that your diet and any food supplements do not exceed the daily calcium requirement too much.

Another important factor in preventing hypercalcemia is the choice of appropriate calcium sources. Even though milk and dairy products are often touted as foods rich in calcium, their impact on our health is controversial.

green vegetables

Green vegetables are a good source of calcium. (Image source: Iñigo De la Maza / Unsplash)

Studies have found that excess dairy intake is associated with higher rates of bone fractures and increased overall mortality. (12) In addition, milk is generally not a very healthy food because it is high in cholesterol, sodium, trans fat, and saturated fat.

It seems that the healthiest way to cover your calcium needs is to eat plant-based foods such as soy, green vegetables, lettuce, nuts and seeds.


Calcium is an essential mineral that we need to get from our diet. The daily requirement intake for an adult is 1000 mg. However, too much calcium can be harmful and increase the risk of cardiovascular disease, impaired kidney function and stroke. A blood calcium level of 3.5 mmol/l and above can lead to a hypercalcemic crisis, which can be life-threatening.

If it is a slight calcium overdose, a low-calcium diet and plenty of fluids are enough to lower the calcium level. If the hypercalcemia is severe, a doctor must administer the appropriate treatment with drugs or phosphates. In the case of a hypercalcemic crisis, only the emergency doctor can help. However, if you eat a balanced diet and only consume certain dietary supplements in moderation, you will not normally suffer from a calcium overdose.


  1. German Society for Nutrition e. V Source
  2. German Society for Nutrition e. V Source
  3. Gesenhues, S. et al.: Practice guidelines for general medicine, Elsevier/Urban & Fischer Verlag, 7th edition, 2014 Source
  4. Herold, G.: Internal medicine, self-published, 2012 Source
  5. (IQWIG) (2018): How can I cover my calcium requirements? (Retrieved: 08.06.2021) Source
  6. Robert Koch Institute (RKI): "Answers from the Robert Koch Institute to frequently asked questions about vitamin D", at (accessed: 08.06.2021) Source
  7. Stahl, A./Heseker, H. (2010): Vitamin A: Physiology, functions, occurrence, reference values ​​and supply in Germany, In: Nahrungsmittels Umschau (9): 481-489, (accessed: 08.06.2021) Source
  8. Classen, M. et al.: Internal medicine, Elsevier/Urban & Fischer Verlag, 6th edition, 2009 Source
  9. Neumeister, B. et al.: Clinic guidelines for laboratory diagnostics, Elsevier/Urban & Fischer Verlag, 4th edition 2009 Source
  10. Xiao Q, Murphy RA, Houston DK, Harris TB, Chow W, Park Y. Dietary and Supplemental Calcium Intake and Cardiovascular Disease Mortality: The National Institutes of Health–AARP Diet and Health Study. JAMA Intern Med. 2013;173(8):639-646.Source
  11. Hypercalcemia / James L. Lewis, III, MD, March 2018 (accessed: 06/08/2021) Source
  12. Karl Michaëlsson et al. (2018): Milk intake and risk of mortality and fractures in women and men: cohort studies, British Medical Journal, DOI: 10.1136/bmj.g6015 Source
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1 comment

Sehr interessanter Artikel! Es ist wichtig zu wissen, wie Calcium im Körper wirkt und was bei einer Überdosierung passieren kann. Besonders aufschlussreich fand ich die Informationen zu den Ursachen einer Hyperkalzämie und wie sie behandelt werden kann. Es ist beeindruckend, wie vielfältig die Funktionen des Calciums im Körper sind. Vielen Dank für diesen informativen Beitrag!


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