Methotrexate is perhaps the most potent medication in the management of psoriasis. It is also an immunosuppressant drug that is used in many autoimmune diseases like rheumatoid arthritis. It acts through decreasing the rate of division of skin cells as well as white blood cells responsible for the condition. It can be given as injections -preferably- or orally. It is, however, only used in patients with severe psoriasis whose condition can’t be controlled by other medications since it comes with its fair share of side effects including severe nausea and vomiting if it is administered orally. It also has a profound effect on the liver, and therefore, alcohol should be restricted during the duration of therapy and regular liver function tests are done.
Methotrexate can also cause fetal damage, so women should be instructed to use effective contraception during the duration of therapy and 6 months afterwards. It can also affect sperms and males and they should also use effective contraception methods for at least 3 months after terminating therapy as well.