The BBC reports 19 people have been treated in hospital, according to Denmark’s SSI health agency. Those involved in the outbreak are aged between two and 92.

All those affected ate Husk brand psyllium husk capsules from batches recalled by manufacturer Orkla Care.

Authorities found traces of salmonella in the products at patients’ homes.

The herbal products are generally used as a laxative. Luise Müller of Denmark’s Statens Serum Institut said it was the first time the agency had found a herbal medicine to be the cause of a salmonella outbreak.

It is not clear which ingredient could have caused the poisoning.