What Is Vitamin Toxicity?

Table of ContentsView AllTable of ContentsWhat Are Vitamins?Vitamin AB VitaminsVitamin CVitamin DVitamin EVitamin KTreatment

Table of ContentsView All

View All

Table of Contents

What Are Vitamins?

Vitamin A

B Vitamins

Vitamin C

Vitamin D

Vitamin E

Vitamin K

Treatment

Vitamin toxicity is common. For example, in 2021, there were 42,784 toxic exposures in children in the United States.Fortunately, most cases do not lead to serious medical outcomes.

In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. Whenchoosing a supplementlook for independently tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.

Fat-Soluble vs. Water-Soluble Vitamins

All essential vitamins are water-soluble except for vitamins A, D, E, and K. These four are fat-soluble, meaning the body can keep them stored within fat deposits for long-term use.

Care should always be taken to use only recommended amounts of supplements. Here’s a review of each of the vitamins and the potential risk of vitamin toxicity for each one, including the possible symptoms, diagnosis, and treatments.

The recommended vitamin A from animal sources andretinoid-based supplementsper day varies for different people:

Adults should avoid taking more than 3,000 mcg RAE (10,000 IU). Keeping daily vitamin A intake near the recommended amounts is the safest choice since chronically taking more can be harmful.

Pregnant people do need to consume vitamin A but they should avoid high doses during pregnancy or while trying to conceive. Too much vitamin A can lead to developmental disturbances in the embryo/fetus, including the eyes, skull, lungs, and heart.

Symptoms of Vitamin A Toxicity

Vitamin A toxicity commonly affects the skin, causing reddening, irritation, and patchy peeling. Chronic, excessive supplement use may lead to more severe symptoms, including:

People treated with retinoids can have elevatedtriglyceridelevels that can cause liver damage, bone loss, and other consequences.

A unique symptom of excess beta-carotene consumption, calledcarotenemia, causes a yellow or orange coloration of the skin, but this condition is reversible and not dangerous.

Causes

Excessive consumption of animal food sources, like liver or fish oil, in addition to supplements high in preformed vitamin A, increases the risk of vitamin A toxicity. Many multivitamins contain both preformed vitamin A and provitamin A, so it is important to identify what kinds are present in these supplements.

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

Some medications will affect how the body absorbs vitamin A. Orlistat, a common weight loss medication, decreases the absorption of fat-soluble vitamins (including vitamin A).Patients taking orlistat should also take fat-soluble vitamin (A, D, E, K) supplements.

Medications calledretinoidsconsist of vitamin A-related compounds and are used for treating ailments affecting the skin, blood, and organ lining. These may increase the risk of toxicity when taken together with vitamin A supplements.

Most of theB vitaminsare important for metabolism. They’re important fo skin, hair, brain, and muscle health. Fortunately, with the exception of vitamins B3 and B6, you most likely will not experience significant vitamin toxicity with their overuse.

Vitamin B1 (Thiamine)

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

Vitamin B1 is not known to be toxic in high doses. It is important for metabolizing glucose and delivering energy to the cells.

Vitamin B2 (Riboflavin)

Vitamin B2, also known as riboflavin, is found in dairy, eggs, meat, salmon, whole grains, and leafy green vegetables. The recommended daily amount 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. It leaves the body quickly when you urinate and there is no known upper limit for dosage.

Vitamin B3 (Niacin)

Vitamin B3, also known asniacin, is found in meat, fish, whole grains, and leafy greens. The recommended daily amount for adults is 16 mg for men and 14 mg for women.

Vitamin B3 is used therapeutically to manage cholesterol.However, people taking it may be at risk of toxicity when taking doses of 50 mg per day or more for a prolonged period of time. Make sure to check your cholesterol levels after 30–60 days of a niacin (B3) protocol.

High one-time doses of vitamin B3 are not known to be toxic. However, B3 should not be taken if you have gout as it can increase uric acid levels. When used in combination with statins, there is a higher risk of muscle-related disorders such asrhabdomyolysis, a serious medical condition occurring when damaged muscle tissue releases chemicals into the blood.

B3 may also worsen peptic ulcer disease. Prolonged overuse of vitamin B3 can cause liver damage, particularly in people with preexisting liver disease.

Vitamin B5 (Pantothenic acid)

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

Vitamin B5 has not been shown to be toxic in high doses. However, some research suggests it can pose a risk to the developing fetus during pregnancy. Higher doses also may worsen symptoms of Alzheimer’s disease in older adults.

Vitamin B6

Vitamin B6is a group of compounds related to pyridoxine, which is found in poultry, pork, fish, whole grains, legumes, and blueberries.

The recommended daily amount is 1.3 mg–2 mg for adults. Vitamin B6 is important to infant growth and, later in life, may play a role in managing stress.

Vitamin B7 (Biotin)

Vitamin B7, also known asbiotin, is found in liver, pork, eggs, dairy, banana, sweet potato, and nuts. The recommended daily amount for adults is 30 mcg.

Vitamin B7 has not been shown to be toxic in high doses, though it may pose a risk to the developing fetus during pregnancy. There’s also some research to suggest biotin is a factor in sudden infant death syndrome but more study is needed.

Vitamin B9 (Folate, Folic Acid)

Vitamin B9, commonly known asfolateorfolic acid, is important for new cell production as well as early brain and spine development of a fetus during pregnancy. It is found in citrus and leafy greens.

The recommended daily amount for adults is 400 mcg. Pregnant people should get 600 mcg, and people who are lactating should get 500 mcg daily.

Folic acid is not generally toxic in high doses, but it can obscure symptoms ofpernicious anemia.

Vitamin B12 (Cobalamin)

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

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

Symptoms of B Vitamin Toxicity

Not all B vitamins will lead to symptoms of toxicity at higher doses. Early symptoms of vitamin B3 toxicity are sometimes called “niacin flush” because it can dilate blood vessels (vasodilation) and lead to reddening of the skin, itchiness, and burning.While harmless, it is an important indicator of vitamin B3 toxicity.

With vitamin B5, some people may experience diarrhea. Extreme doses of vitamin B6 can cause neurological symptoms like numbness and tingling in the extremities. Taking too much may cause loss of coordination, skin lesions, and disrupted digestion.

Allergy to Vitamin B12

Symptoms of Vitamin C Toxicity

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

Vitamin D, also known as calciferol, assists calcium absorption and bone-building. Pre-vitamin D can be produced in the skin, but with more people spending the majority of their time indoors or living at latitudes with seasonally reduced sun, sunlit skin alone may not provide all thevitamin D needed.

Vitamin D is therefore added to foods such as fortified milk, juice, and cereal. Some people may need to take avitamin D supplementto get enough.

The recommended daily amount for adults 31 to 70 years old is 15 mcg (600 IU) and 20 mcg (800 IU) for adults 71 and older.

Symptoms of Vitamin D Toxicity

If you take 100 mcg (10,000 IU) or more of vitamin D supplements daily, you riskvitamin D toxicity, leading to abnormally high levels of calcium in the blood.Symptoms may include:

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

Could You Have Too Much Vitamin D?

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

The recommended daily amount for adults is 15 mg.More study is needed, but there is some evidence that excessive doses can raise the risk of prostate cancer in people with penises. It also may contribute to the risk of bleeding when taking other medications. Talk to your healthcare provider about taking it while receiving cancer treatment.

Vitamin K, also known as phylloquinone and menadione, is a fat-soluble vitamin important for blood clotting. It is found in milk, soy oil, and leafy greens. Supplements are not generally needed except in situations in which absorption is decreased.

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

Avoid Vitamin K supplementation if you are taking or plan to take oral anticoagulants (blood thinners) like warfarin, as they are antagonists.

Vitamin toxicity diagnosis and treatment will depend on the specific type. In general, it’s important to stop taking vitamins that play a role in your symptoms but do so while working with a healthcare provider. They may need to change your medications or take other measures, too.

If you’re diagnosed with chronic vitamin A toxicity based on a blood test, the most important course of action is to reduce vitamin A intake. In most cases, a one-time large dose that leads to acute vitamin A toxicity will occur in children.Inducing vomiting in children is not advised, so contact a healthcare provider or call poison control as soon as possible at 1-800-222-1222.

Why You Might Consider Taking Prenatal Vitamins Even If You’re Not Pregnant

Summary

Many vitamins pose no threat to your health, even at very high doses. But fat-soluble vitamins, including vitamins A, D, E, and K, can build up to levels that cause symptoms when taken at high doses over long periods of time, or if an underlying health condition or a drug interaction affects how your body is using them. In rare cases, the toxicity may be life-threatening.

Vitamins also can cause toxicity with an excessive single dose. If you are concerned about vitamin toxicity, speak with your healthcare provider about your use of vitamin supplements. They can identify associated symptoms, provide appropriate blood testing, and offer treatment if needed.

As a general rule, simply stopping the overuse of supplements may allow the body to correct the imbalance and restore health.

16 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Capital Poison Center.National Poison Control Call Statistics, 2021.

National Institutes of Health Office of Dietary Supplements.Vitamin A and Carotenoids.

Carazo A, Macáková K, Matoušová K, Krčmová LK, Protti M, Mladěnka P.Vitamin A Update: Forms, Sources, Kinetics, Detection, Function, Deficiency, Therapeutic Use and Toxicity.Nutrients. 2021 May 18;13(5):1703. doi:10.3390/nu13051703.

Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006–.Orlistat. 2021

National Institutes of Health Office of Dietary Supplements.Thiamin fact sheet for health professionals.

National Institutes of Health Office of Dietary Supplements.Riboflavin.

National Institutes of Health Office of Dietary Supplements.Niacin fact sheet for health professionals.

Ali MA, Hafez HA, Kamel MA, Ghamry HI, Shukry M, Farag MA.Dietary Vitamin B Complex: Orchestration in Human Nutrition throughout Life with Sex Differences.Nutrients. 2022 Sep 22;14(19):3940. doi: 10.3390/nu14193940.

National Institutes of Health Office of Dietary Supplements.Vitamin C fact sheet for health professionals.

MedlinePlus.Hypervitaminosis D.

National Institutes of Health Office of Dietary Supplements.Vitamin E Fact Sheet for Health Professionals.

National Institutes of Health Office of Dietary Supplements.Vitamin K Fact Sheet for Health Professionals.

National Institutes of Health Office of Dietary Supplements.Vitamin B6 fact sheet for health professionals.

Merck Manual Professional Version.Vitamin A Toxicity.

National Capital Poison Center.Never induce vomiting if a child swallows a poison.

Harvard Health Publishing.Listing of vitamins.National Institutes of Health Office of Dietary Supplements.Vitamin A fact sheet for health professionals.Ross CA.Encyclopedia of Dietary Supplements. Informa Healthcare, 2nd edition.

Harvard Health Publishing.Listing of vitamins.

National Institutes of Health Office of Dietary Supplements.Vitamin A fact sheet for health professionals.

Ross CA.Encyclopedia of Dietary Supplements. Informa Healthcare, 2nd edition.

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