Tylenol, one of the bestselling painkillers here, was the medicine with the highest number of reported side effects over the last five years.

According to the Korea Food and Drug Administration’s report to Rep. Yang Seung-jo of the main opposition Democratic Party, Tylenol ER-Tab manufactured by Johnson and Johnson Korea marked a total of 1,275 cases of adverse effects reported between 2006 and July this year, the highest for a single drug.

Aspirin Protect, prescribed to prevent cardiovascular diseases, and Boryung Astrix Cap followed with 930 and 853 cases, respectively. Oral contraceptive Mercilon was also reported, with 611 cases.

By substance, aspirin led the others with 1,783 adverse effect cases, followed by paracetamol, which is Tylenol’s active ingredient, known as acetaminophen in the U.S. Aspirin is used as a painkiller, fever remedy and for cardiovascular conditions.

Yang said the total number of side effect cases is increasing every year from 5,834 in 2006 to 53,854 in 2010, to 40,631 for the January to July period of this year.

“People need to take extra caution when they take drugs,” the lawmaker said.

By Bae Ji-sook (baejisook@heraldcorp.com)