Hello. Thanks for writing to us at healthcaremagic In my view you are on right treatment for scalp psoriasis and I would suggest that you stick to it. Scalp psoriasis commonly presents as scaly itchy patches. Treatment is based on coal tar+salicylic acid based shampoo like the one you have been recommended. Since psoriasis is a steroid responsive condition therefore topical steroid lotions are usually effective and first choice in scalp psoriasis. The lotion which you have been prescribed contain halobetasol propionate and is a good choice for scalp psoriasis. Probably you also have some scalp infection and therefore you doctor has also prescribed you oral cephalexin to take car of the infection. Hair oil is anyways not advisable for psoriasis; it has not beneficial role in psoriasis and it may favor secondary bacterial infection. Follow up with your dermatologist every 2 weeks. Regards