As vitamin A is usually in the retinol form, the conversion is IU x 0.3 = mcg; thus an 8000 IU dose is equal to 2400 mcg. In our study that used 8000 to 25,000 IU per day we had no evidence of toxicity, including hepatotoxicity.The doses I recommend are roughly 3 times the recommended daily allowance; but this dose is being used for therapeutic reasons and is well below other therapeutic doses of vitamin A.