Complications of megavitamin therapy.

A patient with pancytopenia, severe sensory neuropathy, and a six-year history of excessive vitamin intake showed portal hypertension on evaluation. A liver biopsy revealed hypervitaminosis A. His sensory findings were characteristic of a recently described syndrome of sensory neuropathy secondary to megadoses of vitamin B6. The patient's neuropathy has improved, but his pancytopenia has persisted. The practice of ingesting large doses of vitamins is increasing in a considerable segment of our population. Many claims of therapeutic benefit have been made, but few have been demonstrated in controlled clinical trials. Although there are indications for the use of large dosages of certain vitamins, they are rare. Physicians should be aware of the toxicities of megavitamin therapy.