Tests uncovered that most of the so-called "supplements" for sexual enhancement or slimming sold on overseas websites for Japanese consumers contain medical substances that may damage the user's health, according to a recent study by Japan's health ministry.

The Ministry of Health, Labor and Welfare said although no actual damage has been reported so far, it is warning of possible health risks of such products whose quality and safety have not been confirmed by the Japanese authorities or, probably, those of the producing countries.

The ministry has been requesting the operators of the websites to delete the goods from their product lists, while calling on those who have already bought them to stop taking them immediately.

It detected pharmaceutical ingredients in 78 out of 102 libido-enhancing products.

Among them is a product which contained 96 milligrams of "tadalafil" -- often used in medicaments for the treatment of erectile dysfunction -- more than four times the maximum limit of 20 mg for domestically approved products. Using this could cause severe health problems, according to the ministry.

Twelve items in 49 products publicized as supplements with slimming effects were found to contain substances including "sibutramine," an unauthorized medical component in Japan that can bring about adverse reactions such as blood pressure increase and headache, the ministry said.

To carry out the study, the ministry actually bought the 151 supplement products online in 2017, and analyzed them at the National Institute of Health Sciences.

The ministry also purchased 25 foreign-made medicines, among which it has discovered that one product displayed different ingredients in label from those it actually contained.

The ministry has conducted this kind of study annually since fiscal 2011.