This is a potentially serious problem. It usually occurs by taking more that 50,000-250,000 IU per day for more than 3 months. It can lead to dry skin, mouth sores, vomiting, and poor appetite. Eventually, it can cause increased pressure within the brain, headaches, and problems thinking clearly. It may also lead to an enlarged liver or to liver failure.
is normally a fat-soluble vitamin. It occurs in nature as preformed vitamin A and provitamin
A (primarily beta carotene
). The carotenes are converted into vitamin A in the intestines. Fat-soluble vitamin A can accumulate in the liver
, causing side-effects, but consuming too much carotene
will not result in vitamin A toxicity. Thyroxine
and vitamin E
enhance the conversion of carotene to vitamin A. Water-soluble vitamin A results in higher blood levels, with less accumulation in the liver, and, though hard to find, can be used safely in much higher doses.
Laboratory tests appear unreliable for monitoring toxicity, since serum vitamin A levels correlate poorly with toxicity, and SGOT
are elevated only in symptomatic patients. More importantly, there is concern about the teratogenicity
of massive dosages of vitamin A. Women of child-bearing age should use effective birth control during treatment and for at least one month after discontinuation.
Some may take too much vitamin A at once, absorbed via overdose (or by doing something stupid such as eating polar bear liver
!) This can cause stomach pain, nausea
, vomiting, headache, and difficulty sleeping.
Signs and Symptoms
Chapped lips and dry skin, which may be early symptoms, will generally occur in the majority of patients, particularly in dry weather. The first significant toxic symptom is usually headache followed by fatigue
, emotional lability, and muscle and joint pain.