This is a very personal decision, but many vegetarians are happy to use the potentised remedies prescribed by homeopaths (which, despite some of the other answers given here, are not the same as herbal medicine or supplements). When a remedy is potentised, it is diluted so much that none of the original substance is left. Homeopaths have always been extremely careful about the source of their material - i.e. they would not kill a duck just to obtain the material to make a homeopathic remedy. I don't know what the source of the material would be for the remedy you mention (not one I'm familiar with) although you could find this out from a homeopathic pharmacy. Because of the extreme dilutions used, it is unlikely that more than a very few, perhaps only one, duck hearts or livers have ever been used in the making of this potentised remedy and it may well have been obtained from a duck which died naturally. Most vegetarians will be concerned about two key things - that there is no meat or meat product in what they consume (and that's true for the potentised remedies largely used by homeopaths) and that no suffering has been inflicted in producing the material (also true for potentised remedies). But some people do feel strongly they don't want to ingest anything derived from animals in any way, in which case I would suggest you say this to your homeopath, who will be able to find a plant- or mineral-derived remedy to help you. I had a strictly vegan friend whose homeopath was quite used to ensuring that no animal-related remedies were ever used.