December 2, 2023

Vitamin D Side Effects: Deficiency and Psychological Impacts


Both Excess of Vitamin D and deficiency can lead to side effects and health issues explained in this article.

Vitamin D constitutes one of the most important fundamentals for maintaining overall health. Vitamin D is a fat-soluble vitamin that promotes calcium absorption, regulates bone growth and muscular rigidity, and plays a role in immune function. However, getting adequate amounts of this vitamin from your diet alone may be difficult, as rich natural sources are rare. For these reasons, it’s common for people not to get enough vitamin D. Both Excess of Vitamin D and deficiency can lead to side effects and health issues explained in this article.

Your skin produces vitamin D on exposure to sunlight. However, if you spend most of your time indoors or live at a high latitude, you’ll need to get this vitamin from your diet. Good dietary sources include fatty fish, fish oils, egg yolk, liver, mushrooms.

Vitamin D Types and Uses

It exists in two primary forms:

  • Vitamin D2 (ergocalciferol)
  • Vitamin D3 (cholecalciferol)

The D3 vitamin is only found in animal-sourced foods, whereas D2 mainly comes from plant sources and fortified foods. In addition, your skin makes vitamin D3 on exposure to sunlight.

If you take vitamin D supplements, consider choosing vitamin D3 because our bodies can absorb it more effectively than vitamin D2. 

The Vitamin D capsules come with the IU or ‘international units‘ labelling. 

Under normal circumstances, the recommended daily allowance is 400–800 IU (10–20 micrograms), but standard supplemental doses range from 1,000–2,000 IU (25–50 micrograms) per day. Unless prescribed by a doctor, anything more could be harmful and detrimental to health.

Vitamin D is an essential constituent in maintaining the body’s balance of calcium and phosphorus. It helps in maintaining bone density and the structure of the body. It usually helps treat:

  • Hypophosphatemia
  • Hypoparathyroidism
  • Rickets
  • Brittle bones
  • Asthma
  • Hay fever

Vitamin D supplements are usually recommended for people over the age of 65 to prevent the decay of bones and other age-related complications.

Possible Side Effects of Vitamin D

Although the body needs a stable dose of vitamin D, overdosage can negatively impact physical and psychological health. An overdosage of vitamin D may result in the following problems:

1. Hypercalcemia

With an increase in vitamin D, the intestines absorb more significant amounts of calcium and release it into the body. It leads to hypercalcemia. Most of the problems related to vitamin D have their root in hypercalcemia. The condition occurs when there is a greater calcium density in the blood. An excess calcium density (hypercalcemia) can lead to the following problems and symptoms:

  • Loss of appetite
  • Diarrhoea
  • Unexplained exhaustion
  • High blood pressure
  • Muscle weakness
  • Increased thirst and more frequent urination
  • An irregular heartbeat
  • Reduced reflexes
  • A metallic taste in the mouth 

2. Dehydration

Elevated calcium levels in the blood cause dehydration. It can result in polyuria or irregularly large quantities of urine. When a person passes excessive urine, he loses a considerable amount of water and electrolytes. As a result, they might be prone to dehydration.

While the exact reason is unknown, one of the reasons could be an increase in antidiuretic hormones which creates more significant quantities of urine. The symptoms of moderate dehydration include:

  • Increased thirst
  • Irritability
  • Sunken eyes
  • Dry eyes
  • Restlessness

However, severe dehydration is life-threatening. The symptoms are:

  • A weak or absent pulse
  • Low blood pressure
  • Unexplained exhaustion
  • Very little or no urine output
  • Unconsciousness

3. Kidney Damage

Kidney damage is another major problem caused by excess vitamin D. Hypercalcemia may form small cysts in the body that can cause organ damage and organ failure. In addition, when calcium gets stuck in the kidney tissues, it causes nephrocalcinosis. A study conducted in 2015 shows that it results from vitamin D3 toxicity in the body. The symptoms include:

  • Fever
  • Severe pain in the groin and sides of the back
  • Nausea and vomiting

4. Heart Attack and Irregular Heartbeat

As per a 2012 study, high calcium content in the blood can reduce the ability of the heart cells to perform. As a result, a person with a high concentration of phosphate and calcium develops deposits in the heart valves and arteries. It leads to severe heart health issues. The symptoms of heart complications caused by Vitamin D are:

  • Chest pain
  • Dizziness
  • High blood pressure
  • Exhaustion
  • Irregular heartbeat

5. Lung Damage:

An excessive calcium and phosphate level leads to forming crystals that deposit in soft organs like the lungs. These calcium deposits, also known as ectopic concentrations, impair the organ’s functioning. The symptoms include:

  • Chest pain
  • Trouble breathing
  • Coughing

6. Psychological Impacts

Several studies have shown a direct relationship between the excessive dosage of vitamin D supplements and anxiety. In addition, individuals suffering from psychological illnesses have experienced problematic behaviour to hide the pain symptoms.

Research demonstrates that since there is a direct link between depression and anxiety, Hypervitaminosis D may lead to several neurological disorders such as:

  • Dementia
  • Parkinson’s disease
  • Multiple sclerosis
  • Epilepsy
  • Schizophrenia

There have been direct repercussions of neurological symptoms, which also adversely affects sleep that causes cognitive impairment. One of the primary symptoms is dry eyes, which shows an excess of Vitamin D supplementation in the body.

Vitamin D Side Effects Due to Drug Interaction

Often particular medication is not considered suitable for everyone. Therefore, individuals undergoing specific medical treatments should abstain from vitamin D supplements. People taking the following medicines should consult a doctor before taking vitamin D supplements:

  • Steroids
  • Phenobarbital and phenytoin (medicines to treat epilepsy)
  • Orlistat (a weight loss medication)
  • Cholestyramine (treatment to reduce cholesterol)

Some medications might adversely impact the sensitivity of the supplements and the medical conditions. Therefore, people with the following ailments must contact a doctor before taking the supplements:

  • Primary hyperthyroidism
  • Cancer
  • Sarcoidosis
  • Granulomatous tuberculosis
  • Metastatic bone disease
  • Williams syndrome

Typical Symptoms of Excess Vitamin D Side Effects

Under normal circumstances, 100 micrograms of vitamin D is considered a standard dosage for regular people. If you take anything in excess, it might lead to some side effects. More often than not, people will experience the following symptoms:

  • Unexplained exhaustion
  • Loss of appetite and weight loss
  • Constipation
  • Dry mouth
  • Skin that is slow to return to normal after being pinched
  • Increased thirst and frequency of urination
  • Continuous headaches
  • Nausea and vomiting
  • Reduced reflexes
  • Confusion, disorientation, or trouble thinking
  • An irregular heartbeat
  • Muscle weakness and reduced muscle tone
  • Changes in gait

Excess vitamin D can have adverse impacts on the physiology of an individual. Recurrent toxicity caused by excessive vitamin D has been a known cause for the following problems:

  • Extreme dehydration
  • High blood pressure
  • Slowed growth
  • Trouble breathing
  • Temporary losses of consciousness
  • Heart failure and heart attack
  • Kidney stones and kidney failure
  • Hearing loss
  • Tinnitus (ringing in the ears)
  • Pancreatitis (inflammation of the pancreas)
  • Gastric ulcers
  • Coma

More often than not, these problems have passive effects such as weight loss or weight gain, mood fluctuations and changes in behavioural patterns.

Vitamin D Deficiency

Just as an overdosage is problematic for the body because it causes toxicity, deficiency can also lead to long-term problems if not resolved. Vitamin D deficiency can lead to several body ailments, and the symptoms are easily recognisable. 

For older patients, a daily requirement of 800-2000 milligrams of vitamin D is necessary to continue the stable functioning of the body. Any decrease from this amount may lead to severe vitamin deficiency within the body. However, these problems are usually self resolvable and are solved over time.

The symptoms may include:

  • Muscle Weakness
  • Fatigue
  • Bone pain
  • Depression

The deficiency of Vitamin D may lead to the following:

1. Decreased Bone Density

As per a study, the lack of vitamin D reduces the amount of calcium in the blood. It, in turn, makes the bone brittle. It might also lead to increased bone pain and joint pain conditions.

2. Reduces Immunity

Research confirms that a deficiency in vitamin D is associated with increased autoimmunity and increased susceptibility to infection. Lack of vitamin D can adversely affect the immunity of an individual, given his particular condition. It also results in an increased heart rate and is a prime reason for diabetes. In addition, the reduction in immunity can cause diseases such as multiple sclerosis and other forms of infections. It weakens the body from within and prevents natural disease-fighting capacities.

3. Cancer

While this is incredibly rare, vitamin D deficiency may also be responsible for certain types of colon, prostate or breast cancer. 

Sources of Vitamin D

You can get vitamin D from natural resources, which you can substitute with artificial supplements. Some foods that contain vitamin D are:

  • Fatty fish such as salmon, tuna, and mackerel
  • Cheese
  • Mushrooms
  • Egg yolks
  • Milk
  • Breakfast cereals
  • Orange juice
  • Other dairy products, such as yoghurt
  • Soy drinks


While Vitamin D is usually considered safe during pregnancy and breastfeeding, the recommended amount is under 4000 IU. You should avoid a higher dosage to prevent complications.

In the case of children, vitamin D is considered safe if taken orally in quantity as prescribed by a doctor. However, prolonged use of vitamin D may lead to specific health issues in children. Therefore, children between the ages of 1-3 years should not be given a dosage over 2500 IU and between 4-8 should not have a dosage over 3000 IU. These may otherwise lead to complications such as:

  • Atherosclerosis (hardening of the arteries)
  • Histoplasmosis (Fungal infection)
  • Lymphoma
  • Sarcoidosis

The Bottom Line

Since our bodies need vitamin D in adequate quantities, it is essential to get that from natural foods. However, vitamin D supplements may have an adverse effect. Therefore, you must not take them without the consultation of a physician. In addition, a person stands at a greater risk of experiencing higher toxic levels if they take supplements for an extended period.

A steady increase in vitamin D supplementation leads to increased calcium concentration in blood, leading to common symptoms of nausea and body ache. In addition, It also affects organs like the lungs and kidneys. However, the chances of experiencing the side effects are considerably less since our bodies absorb most of vitamin D from diet and exposure to sunlight. However, if you experience any symptoms mentioned above, consult your physician immediately.

Frequently Asked Questions (FAQs)

Q. How much vitamin D is too much?

A. If you consume less than 100mg of vitamin D per day, it is considered normal. Anything more may lead to body ailments such as hypercalcemia and kidney or lung damage due to excessive calcium concentration in the blood.

Q. Are there any side effects of taking Vitamin D?

A. Yes, there are several side effects of taking vitamin D in excess. Less than 100mg of vitamin D per day is a standard dosage. However, prolonged use of vitamin D supplements can lead to a steady increase of calcium content in the blood. It may cause several ailments like hypercalcemia and lung or kidney damage.

Q. How much vitamin D can you take in one day?

A. Approximately 100 milligrams of vitamin D is a normal dosage. Usually, organic food and the sun are considered the best sources of Vitamin D in the human body. You should only take supplements after consultation with a physician.

Q. What drugs should not be taken with Vitamin D?

A. You should not take the following drugs with vitamin D supplements:

  • Steroids
  • Phenobarbital and phenytoin, which can treat epilepsy
  • Orlistat, a weight loss medication
  • Cholestyramine, which can reduce cholesterol

Q. Can a lack of vitamin D cause weight gain?

A. The lack of vitamin D can cause both weight gain and weight loss. In addition, depending on the person’s physiology, it can trigger hormonal changes that may result in increased or decreased appetite, indirectly triggering the weight gain or loss process.

Q. Can vitamin D deficiency make you sick?

A. Yes, vitamin D deficiency can make you sick since it triggers temporal and hormonal changes. It also affects the lungs and kidneys as well as cause cognitive impairments in adults, which can make you sick.

Q. What happens if your vitamin D is low?

A. A deficiency of vitamin D causes behavioural changes along with the following:

  • Muscle Weakness
  • Fatigue
  • Bone pain
  • Depression

Q. Can low vitamin D cause neurological symptoms?

A. Yes, low vitamin D can cause several neurological symptoms such as depression and anxiety. It may also cause dementia, Parkinson’s disease, multiple sclerosis, epilepsy and schizophrenia.

Q. Does vitamin D affect sleep?

A. No, vitamin D does not directly affect sleep. However, it may cause behavioural patterns that might adversely affect sleep.

Q. Can vitamin D deficiency cause anxiety?

A. Yes, Vitamin D deficiency can cause anxiety because it has psychological impacts. It has a direct interlink between depression and anxiety.

Q. Can vitamin D cause cognitive impairment?

A. Yes, a deficiency in vitamin D can lead to cognitive impairment. However, this is usually treatable. In addition, an increased intake of vitamin D usually leads to problems that resolve after some time.

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