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Vitamin A - Overdosage, Toxicity, Interactions and Cautions

Date reviewed: 5 July 2015 | Date updated: 5 July 2015

• Toxicity
• Overdosage
• Cautions
• Interactions

Toxicity

Vitamin A is toxic in large doses. To avoid vitamin A toxicity, either take the recommended daily intake of Vitamin A or take Betacarotene instead.

Vitamin A toxicity is known as also known as hypervitaminosis A.

Vitamin A toxicity can occur due to excessive intake of vitamin A over a short period (acute toxicity), or higher than normal intake of vitamin A over a long period, where levels of vitamin A build up over time and are not excreted by the body (chronic toxicity).

While acute vitamin A toxicity can be far more dangerous than chronic vitamin A toxicity, both are bad for your health. If you suspect you have had too much vitamin A, see a doctor immediately.

Overdosage

Symptoms of overdosage in children are:

• bone pain
• fontanelle bulging (the soft spot on an infant’s skull)
• irritability
• lethargy
• loss of appetite
• stunted growth

Symptoms of overdosage in adults are:

• blurry vision and headache
• diarrhoea and vomiting
• drowsiness and loss of appetite
• hair loss
• irritability
• lethargy
• skin irritation

Cautions

Certain people should not take high vitamin A supplements without first consulting their doctor for advice:

• Women who are pregnant - women who are pregnant should not take more than the upper tolerable limit of vitamin A due to the risk on the unborn foetus - high levels of vitamin A supplements could cause birth defects
• Women who are breastfeeding - women who are breastfeeding need to consult their doctor about vitamin A supplementation
• People who drink excessive alcohol - the liver may of a person who drinks excessive amounts of alcohol may be over-stressed from the processing of excessive amounts of alcohol and not be able to processes and eliminate vitamin A supplements, possibly causing toxicity effects from a build-up of vitamin A

Interactions

The following are the medications and supplements that are more likely to cause a reaction with vitamin A supplements:

• Antacids - any type of antacids can reduce absorption of vitamin A (as well as any of the other fat-soluble vitamins too)
• Calcium supplements - high levels of vitamin A supplements can reduce the effectiveness of calcium supplements if they are taken at the same time
• Cholestyramine and Colestipol - the medications Cholestyramine or Colestipol, which are used to lower LDL ("bad") cholesterol levels can reduce the rate of absorption of vitamin A from foods
• Neomycin - the antibiotic Neomycin, can reduce the rate of absorption of vitamin A from foods
• Oral contraceptives - the oral contraceptive can increases the amount of vitamin A in the body and could cause some toxicity, so excessive vitamin A supplementation is not recommended
• Retin-A - Retin-A, a medication used for treating facial acne is high in vitamin A, so people taking vitamin A supplements at the same time as this medication will increase their risk for vitamin A toxicity
• Vitamin E - vitamin E supplements work very synergistically with vitamin A supplements, but when the intake of vitamin E supplements is at very high levels, they can deplete the vitamin A stores in the liver and cause a deficiency

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