If your psoriasis is not responding to any other type of treatment, you may want to consider oral or injected prescription medications. These medications can cause severe side effects for some users, so they're used for short periods of time. Because each of these drugs in some way works to suppress your immune system, you may become more susceptible to other forms of illness when undergoing treatment for longer periods of time.
Some oral and injected forms of psoriasis treatment include vitamin A retinoids, methotrexate, cyclospine, hydroxyurea and mmunomodulator drugs, which all reduce the production of skin cells and help to suppress the immune system and thus inflammation of the skin. As always, consult with your physician before undergoing these treatments.