What Is Hypervitaminosis A?
Hypervitaminosis A, or vitamin A toxicity, occurs when you have too much vitamin A in your body.
This condition may be acute or chronic. Acute toxicity occurs after consuming large amounts of vitamin A over a short period of time, typically within a few hours or days. Chronic toxicity occurs when large amounts of vitamin A build up in the body over a long period of time.
Symptoms include visual changes, bone pain, and skin changes. Chronic toxicity can lead to liver damage and increased pressure on the brain.
This condition can be diagnosed using blood tests to check your vitamin A levels. Most people improve simply by decreasing their intake of vitamin A.
Causes of Hypervitaminosis A
Excess amounts of vitamin A are stored in the liver, allowing it to accumulate over time. Most people develop vitamin A toxicity by taking high-dose dietary supplements, or by taking more than the recommended amount over a long period of time. This may be the result of megavitamin therapy, which involves consuming very large doses of certain vitamins in an attempt to prevent or treat diseases. It may also be caused by long-term use of certain acne treatments that contain high doses of vitamin A.
Additionally, liver disease and alcoholism may increase a person’s risk for this condition.
According to the Merck Manual for Health Care Professionals, acute vitamin A toxicity is often the result of accidental ingestion by children (Merck Manual, 2007).
Symptoms of Hypervitaminosis A
Symptoms vary based on whether toxicity is acute or chronic; however headaches and rash are common to both types.
Symptoms of acute vitamin A toxicity include:
- abdominal pain
- increased pressure on the brain
Symptoms of chronic vitamin A toxicity include:
- blurry vision or other visual changes
- swelling of the bones
- bone pain
- poor appetite
- nausea and vomiting
- sensitivity to sunlight
- oily skin and hair
- itchy or peeling skin
- cracked fingernails
- skin cracks at the corners of your mouth
- mouth ulcers
- yellowed skin (jaundice)
- hair loss
- respiratory infection
In infants and children, symptoms may also include:
- softening of the skull bone
- bulging of the soft spot on the top of an infant’s skull (fontanel)
- double vision
- bulging eyeballs
- inability to gain weight
Contact your doctor if you or your child is experiencing any of these symptoms.
The correct amount of vitamin A is crucial for the development of a fetus, specifically the heart, ears, eyes, and limbs. However, excess vitamin A consumption during pregnancy is known to cause birth defects that may affect the eyes, skull, lungs, and heart.
Other potential complications include:
- liver damage
- osteoporosis (a condition causing bones to become brittle, weak, and prone to breaks)
- excessive calcium build-up in the body
- kidney damage due to excess calcium
Diagnosing Hypervitaminosis A
To diagnose this condition, your doctor will perform a physical examination and ask questions about your symptoms and any medications or supplements you are taking. To confirm the diagnosis, your doctor will likely order blood tests to check the levels of vitamin A in your blood.
How Hypervitaminosis A Is Treated
The most effective way to treat this condition is to stop taking high-dose vitamin A supplements. Most people make a full recovery within a few weeks. Complications, such as liver or kidney damage, must be treated independently.
Long Term Outlook
Outlook depends on the severity of the vitamin A toxicity and how quickly it was treated. Most people make a full recovery once they stop taking vitamin A supplements. For those who develop complications, such as kidney or liver damage, outlook will depend on the severity of the damage.
Birth defects caused by excessive amounts of vitamin A are irreversible.
Sources of Vitamin A
You can get most of the vitamin A your body needs from a healthy diet alone. Foods that contain vitamin A include:
- liver and fish oils
- dark fruits
- leafy, green vegetables
- orange and yellow vegetables
- tomato products
- some vegetable oils
- fortified foods, such as cereal
How Much Vitamin A Do You Need?
According to the National Institutes of Health (NIH), the recommended dietary allowances for vitamin A are:
- 0-6 months old: 400 micrograms (mcg)
- 7-12 months: 500 mcg
- 1-3 years: 300 mcg
- 4-8 years: 400 mcg
- 9-13 years: 600 mcg
- 14-18 years: 900 mcg for males, 700 mcg for females
- 14-18 years/pregnant females: 750 mcg
- 14-18 years/breastfeeding females: 1,200 mcg
- 19+ years: 900 for males, 700 for females
- 19+ years/pregnant females: 770 mcg
- 19+ years/breastfeeding females: 1,300 mcg
Taking more than the recommended daily allowance for several months can cause vitamin A toxicity. This condition can occur more quickly in infants and children. (NIH, 2011)