MedlinePlus Medical Encyclopedia: Hypervitaminosis A

Skip navigation


Medical Encyclopedia
Other encyclopedia topics:	A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9

Hypervitaminosis A

Contents of this page:
Illustrations Alternative names Definition Causes, incidence, and risk factors Symptoms Signs and tests	Treatment Expectations (prognosis) Complications Calling your health care provider Prevention

Illustrations

Food guide pyramid

Alternative names Return to top

Vitamin A toxicity

Definition Return to top

Hypervitaminosis is the excessive accumulation of a vitamin; this condition involves too much vitamin A.

Causes, incidence, and risk factors Return to top

There are two types of vitamin A toxicity:

Acute: caused by taking too much vitamin A over a short period of time
Chrinic: occurs when the excess of the vitamin is present over a longer period

In an infant, the sudden intake of too much vitamin A may cause a bulging fontanelle ("soft spot" on the head) and symptoms resembling those of a brain tumor. This group of symptoms is called pseudotumor cerebri and includes a bulging fontanelle, papilledema (swelling of the optic disc), and double vision. Vomiting and drowsiness are common.

The symptoms in adults are less specific. Headache, visual changes, and impaired consciousness suggestive of pseudotumor cerebri may occur. Other symptoms may include nausea, vomiting, dizziness, and blurry vision.

Chronic vitamin A toxicity develops after taking excessive doses of the substance for extended periods. Bone pain and swelling of the bones is common, often associated with high levels of calcium in the blood. Other symptoms include hair loss, high cholesterol, liver damage, and vision problems. Symptoms are often subtle and may include fatigue, malaise, and nausea.

In children, hypervitaminosis A can cause craniotabes (abnormal softening of the skull bones). Irritability, decreased appetite, itchy skin, and poor weight gain are common. There may be skin changes with seborrhea (extremely oily skin and hair) and cracking at the corners of the mouth.

Increased intracranial pressure is seen in both acute and chronic forms.

Symptoms Return to top

Bulging fontanelles (infants)
Bone pain or swelling
Craniotabes (infants and children)
Skin and hair changes
- hair loss
- seborrhea
- cracking at corners of the mouth
Irritability
Decreased appetite
Poor weight gain (infants and children)
Vomiting
Drowsiness

Signs and tests Return to top

Serum vitamin A levels
A history of either acute vitamin A ingestion or long-term ingestion at levels above recommended values
Periosteal calcification (hands)
High blood calcium levels
High serum creatinine (suggestive of kidney damage)

Treatment Return to top

Treatment involves simply stopping the use of excess vitamin A.

Expectations (prognosis) Return to top

Full recovery is the most likely outcome.

Complications Return to top

Failure to thrive
Excessively high calcium levels
Kidney damage due to high calcium
Osteoporosis
Liver damage

Recent studies show that too much vitamin A taken during pregnancy can cause abnormal development in the fetus. Consult your physician about a proper diet.

Calling your health care provider Return to top

Call your health care provider if you think that you or your child may have taken vitamin A in excess or if you have symptoms that may be linked with excess vitamin A.

Prevention Return to top

To avoid hypervitaminosis A, avoid taking more than the recommended daily allowance of this vitamin. Recent emphasis on vitamin A and beta carotene as anti-cancer vitamins may contribute to chronic hypervitaminosis A if well-meaning people increase the dosage of vitamins beyond recommended values. More is not always better!

Update Date: 8/12/2004

Updated by: Aniket R. Sidhaye, M.D., Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician 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. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.