DUBUQUE, Iowa (AP) -- A Dubuque woman who describes herself as an "alternative health care consultant" has been warned by Iowa regulators about practicing medicine without a license.

The Des Moines Register reports that the Iowa Board of Medicine sent a letter earlier this month to Erin Gotz.

The board says it has reviewed information about her use of tuning folks and specialized crystals and her recommendations for high doses of vitamins. The board says it has "serious concerns that the use of such high-dose vitamins may be toxic and could cause serious harm to your clients."

Gotz didn't immediately return a message Monday from The Associated Press.