Put the drug in a container with cold water and let it steep, covered, for 8 - 12 hours (e.g. overnight) at room temperature. Before drinking, the tea can be warmed to drinking temperature. This is a particularly gentle extraction process, but can only be used for a few drugs because the dissolving power of cold water is usually not sufficient. With some drugs, e.g. B. with marshmallow root, the cold extract is preferable because if it was prepared using hot water, the pectin would be dissolved and the starch contained in the root would gelatinize. Senna leaves must also be prepared with cold water because hot infusion would release ingredients that can cause abdominal pain.
In phytotherapy, cold water extracts are used to remove mucilage and essential oils from the medicinal plants in question. To do this, the shredded plant material is poured with cold to lukewarm water. Depending on the plant, the extract is left to stand for up to twelve hours and then strained.
Cold water extracts are also used by gardeners to produce environmentally friendly pesticides. Extracts from nettles have proven particularly useful.