I have just started (4 weeks) on 10mg methotrexate by injection. My problem is I am having severe uncontrollable bouts of diarrhoea. I'm afraid to leave the house at the moment. I have just had a gastroscopy and colonoscopy and they were all clear so I can only assume it is the methotrexate. Anyone else having this problem? It is both duplicating and humiliating. Please help if you can.