Is there something i could buy in the local chemist for this?

after i take a shower i always have really dry itchy skin on my back, shoulders and my face. i also get dundruff and the severity of this varies from day to day and week to week. my gp has prescribed shampoo in the past but nothing seems to work long term. i was wondering if there is anything worth trying and can anyone recommend a shower gel or something that will moisturise my skin in the shower instead of me having to rub on moisturiser after i get out?