Hypervitaminosis AVitamin A toxicity
Hypervitaminosis A is a disorder in which there is too much vitamin A in the body.
Vitamin A is a fat-soluble vitamin that is stored in the liver. There are two types of vitamin A that are found in the diet. Preformed vitamin A is f...
Vitamin A is a fat-soluble vitamin that is stored in the liver. Many foods contain vitamin A, including:
- Meat, fish, and poultry
- Dairy products
- Some fruits and vegetables
Some dietary supplements also contain Vitamin A.
It is rare for vitamin A toxicity to occur just from vitamin A-rich foods. Usually, supplements are involved.
Too much vitamin A can make you sick. Large doses of vitamin A during pregnancy can cause birth defects.
- Acute vitamin A poisoning occurs quickly, most often 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 vitamin A or if they swallow products that contain vitamin A, such as skin cream with retinol in it.
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
- Double vision (in young children)
- Hair changes, such as hair loss and oily hair
- Liver damage
- 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 involves simply stopping supplements (or in rare cases, foods) that contain vitamin A.
Most people fully recover.
Complications can include:
- Excessively 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 abnormal development in the growing baby. Talk to your health care provider about eating a proper diet while you are pregnant.
When to Contact a Medical Professional
Call your provider if you think that you or your child may have taken too much vitamin A, or you have symptoms of excess vitamin A.
How much vitamin A you need depends on your age and gender. 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, avoid taking more than the recommended daily allowance of this vitamin. Emphasis on vitamin A and beta carotene as anticancer vitamins may contribute to chronic hypervitaminosis A if people take more than is recommended.
The beta-carotene test measures the level of beta-carotene in the blood.
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 www.ncbi.nlm.nih.gov/pubmed/25057538.
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 218.
Ross AC, Tan L. Vitamin A deficiencies and excess. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 48.
Vitamin A source - illustration
Like most vitamins, vitamin A may be obtained in the recommended amount with a well-balanced diet, including some enriched or fortified foods.
Vitamin A source
Review Date: 2/22/2018
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.