Hi,
Sunlight and water may make a difference in how psoriasis and psoriatic arthritis look and feel. The following natural treatments may also prove to be effective: aloe vera, apple cider vinegar, capsaicin, emu oil, evening primrose oil, oats, and tea tree oil.
You can read more about this through this link: http://www.psoriasis.org/treatment/psoriasis/
Take care and regards.