Vitamin A toxicity, also referred to as hypervitaminosis A, occurs when an adult consumes too much vitamin A over an extended period of time. According to the Merck Manuals Online Medical Library, vitamin A toxicity usually presents after months of excess consumption. Vitamin therapy is the most common cause, but toxicity can also develop as a result of ingesting excess amounts of vitamin A in the diet.
Symptoms
Vitamin A toxicity in adults can result in a variety of symptoms that affect numerous body systems. These symptoms include blurred vision, bone pain, decreased appetite, dizziness, fatigue, headache, irritability, nausea, vision changes and vomiting, according to MedlinePlus. Vitamin A toxicity can also cause skin and hair changes, such as hair loss, oily skin, peeling skin and yellow skin discoloration. Some adults with vitamin A toxicity may also experience an increase in intracranial pressure, which is a rise in pressure inside of the skull.
Treatment
Treatment for vitamin A toxicity involves stopping the consumption of too much vitamin A. This includes a combination of limiting vitamin A in the diet and avoiding taking supplements that contain high amounts of vitamin A.
Prognosis
Most adults with vitamin A toxicity fully recover after drastically reducing intake of vitamin A. According to the Merck Manuals Online Medical Library, symptoms usually disappear within one to four weeks. If left untreated, vitamin A toxicity can lead to a significant increase in calcium levels, which can cause kidney damage and liver damage.
Tolerable Upper Intake Level
The Food and Nutrition Board provides a tolerable upper intake level, or UL, for vitamins that are known to cause adverse health effects in high amounts. The UL is defined as the highest amount of the vitamin that can be consumed each day without causing any changes to health. The UL for vitamin A is 3,000mcg per day for adults ages 19 and older.
Considerations
Consumption of excess amounts of vitamin A by pregnant women can cause birth defects during fetal development. Pregnant women should avoid foods that are fortified with vitamin A and vitamin A supplements that contain more than 1,500mcg of vitamin A, according to the Linus Pauling Institute at Oregon State University.
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