Vitamin toxicity: causes, diagnosis, treatment.


Vitamins are essential nutrients that keep the body healthy, but the good things can be overstated. Taking excessive amounts of any of the vitamins can cause serious health problems, a condition commonly called hypervitaminosis or vitamin toxicity. Certain diets can also lead to overconsumption of vitamins.

Improper use of vitamin supplements can be very dangerous. Certain medications can also increase the risk of vitamin toxicity, either by increasing the body's absorption of the vitamin or by containing vitamin compounds.

In 2017, vitamins were responsible for 59,761 toxic effects in the United States, 42,553 of which were in children under the age of 5, according to the National Poisoning Data System. Fortunately, there are far fewer serious health outcomes associated with vitamin toxicity. However, it is important to recognize the symptoms and understand the causes of vitamin toxicity.

What are vitamins?

Vitamins are a group of essential nutrients vital to keeping your body healthy. The correct amount is important for maintaining healthy brain, bones, skin, and blood. Some vitamins also help in the absorption of food. Many vitamins are not made by the body and must be obtained from food or vitamin supplements, including:

  • Vitamin A
  • Vitamin B1 (thiamine)
  • Vitamin B2 (riboflavin)
  • Vitamin B3 (niacin)
  • Vitamin B5 (pantothenic acid)
  • Vitamin B6
  • Vitamin B7 (biotin)
  • Vitamin B9 (folic acid, folic acid)
  • Vitamin B12 (cobalamin)
  • Vitamin C (ascorbic acid)
  • Vitamin D (calciferol)
  • Vitamin E (as alpha-tocopherol)
  • Vitamin K (phylloquinone, menadione)

Fat soluble and water soluble vitamins

The main difference that determines the danger of an overdose is whether the vitamin is fat or water soluble. Water soluble vitamins are used by the body as they are digested and are generally not absorbed by any body tissue for a long period of time.

All essential vitamins are soluble in water, with the exception of vitamins A, D, E, and K. These four are fat-soluble, which means that the body can store them in fat for long-term use.

Because of the way the body absorbs and uses vitamins, some vitamins pose less risk from a single toxic dose. They only cause health problems when taken continuously in high doses for many days or in very extreme doses, usually due to improper use of supplements. Fat-soluble vitamins are rapidly absorbed by the body and can pose an immediate health risk when taken in moderate to extreme doses.

Unless directed by your doctor, you should never take more than the recommended daily dose of a multivitamin or vitamin supplement. While some diseases and conditions can be alleviated with increased vitamin intake, you should always consult your doctor before following high-dose vitamin regimens.

Care should always be taken to use only the recommended amounts of supplements. Let's look at each of the vitamins and the potential risk of vitamin toxicity for each, including possible symptoms, diagnosis, and treatments.

Vitamin A

Vitamin A is used by the body to improve vision, immune response, and normal organ function when consumed in moderation. It is a fat-soluble vitamin found in high concentrations in the liver, kidneys, and fish oil of animals, and in moderate concentrations in dairy products and eggs. Vegetables like sweet potatoes and carrots are also moderate sources of vitamin A.

Animal products contain preformed vitamin A, which is easily absorbed by the body during digestion, while plant products often contain carotenoids, often called provitamin A, which can be converted to vitamin A in the liver.

The amount of vitamin A in a food or supplement is indicated by retinol activity equivalents (RAE), a measure of how easily various provitamin A compounds, such as beta-carotene, are converted into vitamin A used by the body . It can also be listed in International Units (IU), but FDA regulations require that new food labels indicate the amounts in micrograms (mcg) of RAE.

The recommended daily values for animal-based vitamin A and retinoid supplements vary from person to person:

  • Men over 18 years of age : 900 mcg RAE (3000 IU)
  • Women over 18 years: 700 mcg RAE (2333 IU)
  • Pregnant women over 18 years : Contraindicated (not recommended) in pregnancy
  • Nursing people : 1300 mcg RAE

Adults should avoid taking more than 3,000 mcg of RAE (10,000 IU). Keeping your daily vitamin A intake near the recommended level is the safest option, as taking more vitamin A daily can be harmful. Pregnant women should avoid taking vitamin A supplements during pregnancy or when trying to conceive, as they can have teratogenic effects, leading to poor embryonic / fetal development.


Vitamin A toxicity generally affects the skin and causes redness, irritation, and patchy scaling. Chronic overuse of supplements can lead to more serious symptoms, including:

These serious symptoms correspond to long-term effects on bone health and possible liver damage.

A unique symptom of excessive beta-carotene intake, called carotenoderma, causes a yellow or orange discoloration of the skin, but this condition is not dangerous.


Consuming too much animal products such as liver or fish oil, in addition to supplements rich in preformed vitamin A, increases the risk of vitamin A toxicity. Many multivitamins contain both vitamin A and provitamin A, making it It is important to determine what types are contained in these supplements.

Plant-based beta-carotene, the provitamin A found in carrots, is metabolized differently than vitamin A. It is not responsible for any of the serious symptoms of vitamin A toxicity.

Some medications affect the way the body absorbs vitamin A. Orlistat, a common weight loss drug, reduces the absorption of fat-soluble vitamins (including vitamin A). Patients taking orlistat must also take certain liposomal forms of fat-soluble vitamins (A, D, E, K) to replenish what the drug is removing from the body.

Medications called retinoids are made up of compounds related to vitamin A and are used to treat conditions that affect the skin, blood, and mucous membranes of organs. They can increase the risk of toxicity when taken with vitamin A supplements.

Watch out

If you have been diagnosed with chronic vitamin A toxicity based on a blood test, the most important action is to reduce your vitamin A intake. In case of a high toxic dose, you should take activated charcoal. If the activated charcoal is depleted and you cannot get to the hospital in an hour, use ipecacuum to induce vomiting. In the event of a vitamin overdose, you should always contact Poison Control as soon as possible at 800-222-1222.

Group B vitamins

Most of the B vitamins are important for metabolism. It is associated with healthy skin, hair, brain, and muscles. Fortunately, with the exception of vitamins B3 and B6, you most likely will not experience significant vitamin toxicity when consumed in excess.

Vitamin B1 (thiamine)

Vitamin B1, also known as thiamine, is found in beef, pork, whole grains, legumes, nuts, and sunflower seeds. The recommended daily intake for adults is 1.2 mg (milligrams) for men and 1.1 mg for women.

Vitamin B1 is not toxic in high doses.

Vitamin B2 (riboflavin)

Vitamin B2, also known as riboflavin, is found in dairy products, eggs, meat, salmon, whole grains, and green leafy vegetables. The RDA for adults is 1.3 mg for men and 1.1 mg for women.

Vitamin B2 has not been shown to be toxic in high doses.

Vitamin B3 (niacin)

Vitamin B3, also known as niacin , is found in meats, fish, whole grains, and leafy vegetables. The recommended daily intake for adults is 16 mg for men and 14 mg for women.

Vitamin B3 is used therapeutically to lower cholesterol levels. However, people who take it may be at risk of poisoning if they take doses of 50 milligrams (mg) per day or more for a long period of time. Make sure to check your cholesterol after 30 to 60 days of taking niacin (B3).

If you are pregnant, do not take too much vitamin B3 as it can cause birth defects.

Single high doses of vitamin B3 are not toxic. However, you should not take B3 if you have gout, as it can increase your uric acid levels. And when used in combination with statins, there is an increased risk of myopathy, diseases that affect the muscles that control voluntary body movements, and rhabdomyolysis, a serious condition that occurs when damaged muscle tissue releases chemicals into the bloodstream. B3 can also make peptic ulcer disease worse.

The first symptoms of vitamin B3 poisoning are sometimes called "niacin flush" because it can dilate blood vessels (vasodilation) and cause redness, itching, and burning of the skin. Although it is harmless, it is an important indicator of vitamin B3 toxicity. Long-term excessive intake of vitamin B3 can cause liver damage, especially in people with pre-existing liver disease.

Vitamin B5 (pantothenic acid)

Vitamin B5, also known as pantothenic acid , is found in chicken, egg yolks, dairy products, whole grains, legumes, mushrooms, cabbage, cabbage, and broccoli. The recommended daily intake for adults is 5 mg.

Vitamin B5 has not been shown to be toxic in high doses, but in extreme doses it can cause diarrhea.

Vitamin B6

Vitamin B6 is a group of compounds associated with pyridoxine found in poultry, pork, fish, whole grains, legumes, and blueberries. The recommended daily dose for adults is 1.3 to 2 mg.

Additional doses of more than 100 mg per day are not recommended for adults, except for therapeutic uses. Extreme doses of 1000 to 6000 mg taken over a prolonged period of time can adversely affect the brain and cause neurological symptoms such as numbness and tingling in the extremities.

Taking too much can lead to loss of coordination, skin damage, and indigestion. Symptoms usually resolve after stopping vitamin supplements.

Vitamin B7 (biotin)

Vitamin B7, also known as biotin , is found in liver, pork, eggs, dairy products, bananas, sweet potatoes, and walnuts. The recommended daily intake for adults is 30 mcg.

Vitamin B7 has not been shown to be toxic in high doses.

Vitamin B9 (folic acid, folic acid)

Vitamin B9, commonly known as folic acid or folic acid , is important for the production of new cells and for the early development of the brain and spinal column of the fetus during pregnancy. It is found in citrus fruits and green leafy vegetables.

The recommended daily intake for adults is 400 mcg. Pregnant women should take 600 mcg and breastfeeding people 500 mcg per day.

High-dose folic acid is generally non-toxic, but it can hide the symptoms of pernicious anemia.

Vitamin B12 (cobalamin)

Vitamin B12 , also known as cobalamin, is found in dairy products, eggs, fish, poultry, and meat. The recommended daily intake for adults is 2.4 mcg.

Vitamin B12 has not been shown to be toxic in high doses.

Vitamin C

Vitamin C , also known as ascorbic acid, is used by the body as an antioxidant to prevent cell damage and help the growth and repair of tissues in the body. It is found in citrus fruits, potatoes, peppers, and herbs. The recommended daily intake for adults is 90 mg for men and 75 mg for women.

Vitamin C is generally not considered toxic, but large doses of 2,000 mg per day can interfere with digestion, causing diarrhea, cramps, and nausea .

Vitamin D

Vitamin D, also known as calciferol, promotes calcium absorption and strengthens bones. Previtamin D can be produced in the skin, but as more people spend most of their time indoors or living in latitudes with decreasing amounts of seasonal sunlight, solar skin alone may not provide all the vitamin D they need. Therefore, vitamin D is found in many products such as fortified milk, fortified juice, cereals, and fish, and is available as a supplement.

The RDA for adults 31 to 70 years old is 15 mcg (600 IU) and 20 mcg (800 IU) for adults 71 years of age and older.

If you take 100 mcg (10,000 IU) or more of vitamin D supplements a day, you run the risk of vitamin D poisoning, leading to abnormally high levels of calcium in your blood. Symptoms can include kidney stones, nausea, repeated vomiting, constipation, excessive thirst, excessive urination, confusion, and weight loss.

Taking high doses has also been linked to the risk of cancer, heart problems, and an increased risk of bone fractures.

The diagnosis can be made with blood and urine tests to determine calcium, vitamin D, and phosphorus. It is recommended to stop taking vitamin D for treatment, but other treatments may be required in severe cases.

Vitamin E

Vitamin E, also known as alpha-tocopherol, is a group of eight related compounds that are used as antioxidants to protect the body's cells from damage. It is found in fish, vegetable oil, nuts, seeds, wheat, and leafy greens.

The recommended daily intake for adults is 15 mg.

Taking 300 mg or more of supplements a day can increase men's risk of prostate cancer, stroke, and bleeding .

Vitamin K

Vitamin K, also known as phylloquinone and menadione, is a fat-soluble vitamin essential for blood clotting. It is found in milk, soybean oil, and leafy vegetables. Supplements are generally not needed except in situations where absorption is reduced.

The recommended daily intake for adults is 120 mcg for men and 90 mcg for women.

Avoid taking vitamin K supplements if you are taking or just taking oral anticoagulants (blood thinners) like Coumadin (warfarin) because they are antagonists.

Get the word of drug information

If you are concerned about vitamin toxicity, talk to your doctor about how you are taking vitamin supplements. Associated symptoms and an appropriate blood test will be able to be identified and, if necessary, treatment will be arranged. In general, simply stopping excessive supplementation can allow the body to correct imbalances and regain health.

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