Skiplink Navigation

Main Features

Weed contamination Herbal products to be tested for toxic alkaloid

The alkaloids occur naturally in some plants and is only toxic above a certain dose and through prolonged exposure


All herbal products containing specific plant species will need to undergo testing for pyrrolizidine alkaloids that can damage the liver, Switzerland’s medicine regulatory body Swissmedic has announced. 

Most of the herbal plant species associated with alkaloid-producing weeds are cultivated in Europe and are commonly used in herbal teas. 

The list includes St. John’s Wort (Hyperici herba), passionflower herb (Passiflorae herba), camomile (Matricariae flos), lady’s mantle (Alchemillae herba), liquorice root (Liquiritiae radix), balm leaf (Melissae folium), peppermint (Menthae piperitae folium), sage (Salviae folium), dandelion with root (Taraxaci herba cum radice), and thyme (Thymi herba).

end of infobox

The plant species listed do not contain the alkaloids themselves but products containing them could due to unintentionally harvested weeds. As a result, all companies using these plants in their herbal formulations will be required to demonstrate that care has been taken to avoid cross-contamination by weeds during the harvesting process. 

“Producers will have to take extra care to identify weeds and eliminate them by using special herbicides or treating the soil before sowing seeds,” Daniel Herren of Swissmedic’s market surveillance department told 

Swissmedic has set the maximum limit for pyrrolizidine alkaloids at one microgram (a millionth of a gram) relative to the maximum daily dose for the herbal product. The regulatory body will also begin random checks from mid-2017 to check compliance. 

The issue of weeds being responsible for pyrrolizidine alkaloids was first raised in 2013 by the German Federal Institute for Risk Assessment. In May 2016, the European Medicines Agency issued guidelines on tackling the problem.

Neuer Inhalt

Horizontal Line

SWI on Instagram

SWI on Instagram

SWI on Instagram

subscription form

Form for signing up for free newsletter.

Sign up for our free newsletters and get the top stories delivered to your inbox.

Click here to see more newsletters