First Lady Barbara Bush is taking medication to control a thyroid disorder that produced an eye irritation and caused her to joke she would have dropped a few dress sizes had the condition gone unchecked.

After taking the medication for four days, Mrs. Bush has "noticed marked improvement in her eye symptoms," her press office said Wednesday in a statement.The statement said Mrs. Bush suffers from Graves disease and sought treatment after "mild swelling and irritation of the eyes and some loss of weight."

Mrs. Bush told a group of reporters Wednesday that she did not know about the overactive thyroid condition until her eyes started bothering her, although she had lost about 18 pounds over the past several months. "The thyroid just went wacko," she said.

"Now please, don't have me dying," she joked.