psoriasis has a symptom of all three doshas.pittaj symptoms is also there.according to charak/chikitsa, vamana is for kaphapradhan kustha,dhrutpan for vatapradhan kustha and virechana,raktamokshana for pitta pradhan kustha. so vaman,virechana and dhritpana is the treatment in psoriasis. some things of ayurveda is difficult to explain in modern terminology.
dosage of virechana dravya can be decided according to kostha. if you take erand oil as virechana dravya ,dosage will be like, mridu kosthi=6 to 12 gm madhya kosthi=24 to 60 gm krur kosthi=72 to 120 gm
virechna helps both in pitta and kapha dosha. lets understand the ayurvedic mode of action first that will be more helpful.rest if u go for virechana after snehpaan then try ruksh virechna. decide dose according to koshtha and vegas.
Virechana has Pitta shodhana property. In Kushta our acharyas recommend regular shodhana of the body. In Kushta mainly vitiated dosha are pitta, kapha along with vata and also rakta. Virechna will help in shodhana of pitta as well as kapha. Please refer Ayurvedia Panchakarma Book.
well doctor, understanding a psoriasis as a autoimmune disorder, immune modulations is what required to treat it. let me put it in this way, AaMA- means apakva anna rasa, that can be compared to the metabolic byproducts like free radicals,these free radicals have great affinity towards fatty acids, and the each cell wall is made up of fatty layer,there by affect the cellular metabolism.in the long run sets in as disease.this can be correlated with many of autoimmune disorder.( thats why aama is root cause of vyadhi) when we give snehapanam, it helps to bind out those free radicals which are freely circulating in the blood, there by preventing the effect of free radicals on cellular metabolism. after samyak swedana the these are brought back to stomach/intestines through hepato-entric cirulation, there by helping the immune modulation.after virechan these toxins are expelled out of the body. regading the dose of virechana dravya, you need to stick to the basics like kosts, agni, bala( rogi and roga) etc.refer text for the same.