Because it has been studied quite a bit, good information about vitamin A dosing is available. For some of the less studied uses, the most effective (and safe) doses have not yet been established. Both Recommended Dietary Allowances (RDAs) and Tolerable Upper Intake Levels (UL) have been established for the vitamin.
Most people do not experience side effects with this vitamin, as long as the maximum dosage is not exceeded. Taking too much, however, can result in significant vitamin A toxicity. Some side effects may include:
Written by/reviewed by: Kristi Monson, PharmD;Arthur Schoenstadt, MD
Last reviewed by: KristiMonson, PharmD;
List of references (click here):
Jellin JM, editor. Pharmacist's Letter/Prescriber's Letter Natural Medicines Comprehensive Database Web site. Available at: http://naturaldatabase.com/. Accessed October 6, 2008.
National Institutes of Health. Office of Dietary Supplements. Dietary supplement fact sheet: Vitamin A and carotenoids (4/23/2006). NIH Web site. http://ods.od.nih.gov/factsheets/vitamina.asp. Accessed October 7, 2008.
Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002. Available at: www.nap.edu/books/0309072794/html/. Accessed October 6, 2008.
Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 7th ed. Philadelphia (PA): Lippincott Williams & Wilkins;2005.
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