Health Encyclopedia

Hypervitaminosis A

Definition

Hypervitaminosis A is a disorder in which there is too much vitamin A in the body.

Alternative Names

Vitamin A toxicity

Causes

Vitamin A is a fat-soluble vitamin that is stored in the liver. Many foods contain vitamin A, including:

Meat, fish, and poultry (egg yolks)
Dairy products
Some fruits and vegetables

Some dietary supplements also contain vitamin A.

Supplements are the most common cause of vitamin A toxicity. It tends not to occur just from eating vitamin A-rich foods.

Too much vitamin A can make you sick. Taking large doses during pregnancy can cause birth defects.

Acute vitamin A poisoning occurs quickly. It can happen when an adult takes several hundred thousand international units (IUs) of vitamin A.
Chronic vitamin A poisoning may occur over time in adults who regularly take more than 25,000 IU a day.
Babies and children are more sensitive to vitamin A. They can become sick after taking smaller doses of it. Swallowing products that contain vitamin A, such as skin cream with retinol in it, can also cause vitamin A poisoning.

Symptoms

Symptoms may include:

Abnormal softening of the skull bone (in infants and children)
Blurred vision
Bone pain or swelling
Bulging of the soft spot in an infant's skull (fontanelle)
Changes in alertness or consciousness
Decreased appetite
Dizziness
Double vision (in young children)
Drowsiness
Hair changes, such as hair loss and oily hair
Headache
Irritability
Liver damage
Nausea and vomiting
Poor weight gain (in infants and children)
Skin changes, such as cracking at corners of the mouth, higher sensitivity to sunlight, oily skin, peeling, itching, and yellow color to the skin
Vision changes

Exams and Tests

These tests may be done if a high vitamin A level is suspected:

Bone x-rays
Blood calcium test
Cholesterol test
Liver function test
Blood test to check vitamin A level
Blood test to check other vitamin levels

Treatment

Treatment involves simply stopping supplements (or in rare cases, foods) that contain vitamin A.

Outlook (Prognosis)

Most people fully recover.

Possible Complications

Complications can include:

Very high calcium level
Failure to thrive (in infants)
Kidney damage due to high calcium
Liver damage

Taking too much vitamin A during pregnancy may cause birth defects. Talk to your health care provider about eating a proper diet while you are pregnant.

When to Contact a Medical Professional

You should contact your provider:

If you think that you or your child may have taken too much vitamin A
You have symptoms of excess vitamin A

Prevention

How much vitamin A you need depends on your age and sex. Other factors, such as pregnancy and your overall health, are also important. Ask your provider what amount is best for you.

To avoid hypervitaminosis A, don't take more than the recommended daily allowance of this vitamin. Check the ingredients of all your medicines to be sure you are not taking vitamin A from more than one source.

Some people take vitamin A and beta carotene supplements in the belief it will help prevent cancer. This may lead to chronic hypervitaminosis A if people take more than is recommended.

References

Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academies Press; 2001. PMID: 25057538 pubmed.ncbi.nlm.nih.gov/25057538/.

James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM. Nutritional diseases. In: James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM, eds. Andrews' Diseases of the Skin. 13th ed. Philadelphia, PA: Elsevier; 2020:chap 22.

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 205.

Roberts NB, Taylor A, Sodi R. Vitamins and trace elements. In: Rifai N, ed. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Philadelphia, PA: Elsevier; 2018:chap 37.

Ross AC. Vitamin A deficiencies and excess. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 61.

Review Date:1/9/2022
Reviewed By:Robert Hurd, MD, Professor of Endocrinology and Health Care Ethics, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.