vitamin A toxicity
a condition caused by excessive intake of vitamin A (retinol). A large overdose of vitamin A—500,000 IU or more—can cause headache, vomiting, bone pain, weakness, blurred vision, irritability, and skin flaking. Long-term intake of 100,000 IU or more per day can also lead to toxicity. Symptoms include hair loss, headache, bone thickening, enlarged liver and spleen, anemia, menstrual problems, stiffness, joint pain, weakness, and dry skin. Although high doses of beta-carotene (which can be converted to vitamin A in the body) are not toxic, they can lead to a distinctive deep yellow pigmentation of the skin.