Methotrexate is a very useful medication for the management of numerous types of cancer (including cancer of breast and uterus), leukaemia, severe psoriasis, severe rheumatoid arthritis and several other unusual diseases. The tablet dosage must be individualised for each patient by doctor depending on the disease, severity and weight of patient. It is often given once a week.
Methotrexate must not be used in pregnancy unless mother’s life is at risk, as the foetus may be damaged. Breastfeeding must be ceased before use, but it may be used in children if medically essential.
Use it with caution in infection, active infection, peptic ulcer and ulcerative colitis, and not at all if suffering from severe liver or kidney disease, significant infection, bone marrow disease, low level of white blood cells, low level of blood platelets, significant anaemia, immune deficiency (e.g. AIDS) or alcoholism.
Regular blood tests to check blood cells and liver function are essential, and adequate contraception must be used by women while methotrexate is being taken.
Common side effects include mouth ulcers, nausea, belly pains, diarrhoea, while less commonly tiredness, chills, dizziness, reduced resistance to infection, rash and infertility occur. Yellow skin (jaundice), unusual bleeding or bruising, bone marrow damage and vision changes are serious complications.
This medication interacts with NSAID, aspirin, sulfonamides, phenytoin, tetracyclines, chloramphenicol, folic acid, probenecid, co-trimoxazole, NSAIDs, drugs used to lower cholesterol levels, other cytotoxics, echinacea and willow bark.
Most patients are required to take folate while using methotrexate in order to prevent some side effects.
Despite risk of significant side effects, methotrexate may save the life, or improve the quality of life, of many patients.