Worth to try are extracts from Symphtum species (steroidal glycosids) and extracts from alantoin-rich plants for example Echium vulgaris + water extracts from fresh Chelidonium maius or maybe fresh Chelidonium pulp with addition of fresh Stachys sp. extracts.
There are drugs available from these plants but it depends and vary from country to country. Many good quality pharmacognostical drugs are available in Switzerland and Germany. But the best ones with most potent activity are the ones that you carefully prepare from fresh plants, especially if You know what you're doing. I saw this pattern in many skin conditions: making extracts from fresh plants collected from nature directly have best results.
hydro-alcoholic are best ones for Stakhys; water extracts are good too but must be used directly after extraction; essential oil diluted in water are great in many skin diseases from various of plants;