Rancidity of several anti-psoriatic drugs of AYUSH (Ayurveda & Siddha) were studied and the ill effects of acid value was established by free radical scavenging assay, nitric oxide inhibition, anti-glycation, anti-angiogenesis and fibroblast toxicity. Our findings clearly show that rancidity not only produced severe side effects but also modified the therapeutic constituents from herbal source thus making the Ayush preparations more harmful to the psoriatic patients than as remedial. Several anti-psoriatic oils were compared with Dr. JRK’s 777 oil and Psorolin oil. Findings clearly show that the Dr. JRK’s 777 oil and Psorolin oil is the best, safe and effective drug for psoriasis than many other Ayush oils available in the market. Details are presented in the paper.