Hypervitaminosis A
Vitamin A toxicity
Hypervitaminosis A is a disorder in which there is too much vitamin A in the body.
Like most vitamins, vitamin A may be obtained in the recommended amount with a well-balanced diet, including some enriched or fortified foods.
Causes
Vitamin A is a fat-soluble vitamin that is stored in the liver. Many foods contain vitamin A, including:
- Meat, fish, and egg yolks
- Dairy products
- Some fruits and vegetables
Some dietary supplements also contain vitamin A.
Taking too many supplements is 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 IUs 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
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, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 199.
Office of Disease Prevention and Health Promotion website. Dietary reference intakes.
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.
Sodi R. Vitamins and trace elements. In: Rifai N, Chiu RWK, Young I, Burnham Carey-Ann D, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. St Louis, MO: Elsevier; 2023:chap 39.
Version Info
Last reviewed on: 2/28/2024
Reviewed by: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
