Scientists have added a new discovery to the list of reasons why patients should not seek impotence treatment from an untrusted online source – the pill you would be popping might contain poison, literally.

According to a leading English-language newspaper from Sweden, the country's Medical Products Agency, together with customs officials and the police, recently seized 6,500 impotence drugs one of which was found to contain a potentially lethal substance called strychnine – commonly used in rat poison. Some of the other erectile dysfunction drugs also contained lower or higher dosages of sildenafil, as well as unspecified ingredients, the source learns.

The drug that concerned the authorities the most was Penisole, an herbal product sold on the market as a libido enhancing supplement. This highly toxic substance is banned in Sweden from the 1970s, the source discloses, adding that the Medical Products Agency has now issued a public notice to make people aware of the dangers of buying erectile dysfunction drugs from suspicious websites.

Commenting on the confiscation of Penisole and 50 different brands of medication, chief of medicine of the Swedish Poisons Information Centre Mark Personne told the news source that the authorities are justifiably worried over the fact that anybody looking for a convenient erectile dysfunction treatment online can easily set foot into the trap set by fake drug dealers.

Lab department manager at the Medical Products Agency Monika Johansson told a local daily that customers do not only risk their health by using duplicate medicines, but also pay more for poor quality treatment and suffer the consequences later on.