Hypervitaminosis A is having too much vitamin A in the body.
Vitamin A toxicity
Causes, incidence, and risk factors
There are two types of vitamin A hypervitaminosis:
- Acute -- caused by taking too much vitamin A over a short period of time
- Chronic -- occurs when too much of the vitamin is present over a longer period
Chronic vitamin A toxicity develops after taking too much vitamin A for long periods.
- Abnormal softening of the skull bone (craniotabes -- infants and children)
- Blurred vision
- Bone pain or swelling
- Bulging fontanelle (infants)
- Changes in consciousness
- Decreased appetite
- Double vision (young children)
- Increased intracranial pressure
- Liver damage
- Poor weight gain (infants and children)
- Skin and hair changes
- Vision changes
Signs and tests
- Bone x-rays
- Blood calcium test
- Cholesterol test
- Liver function test
- Blood test to check vitamin A levels
Treatment involves simply stopping the use of too much vitamin A.
Most people fully recover.
- Excessively high calcium levels
- 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 developing baby. Talk to your health care provider about eating a proper diet while you are pregnant.
Calling your health care provider
Call your health care provider if you think that you or your child may have taken too much vitamin A, or you have symptoms of excess vitamin A.
To avoid hypervitaminosis A, avoid taking more than the recommended daily allowance of this vitamin. Recent emphasis on vitamin A and beta carotene as anticancer vitamins may contribute to chronic hypervitaminosis A, if people take more than is recommended.
Zile M. Vitamin A deficiencies and excess. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 45.
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 237.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.