Methotrexate Sodium package insert / prescribing information for healthcare professionals. Includes: indications, dosage, adverse reactions and pharmacology. Learn about methotrexate usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancies. Methotrexate is used to treat certain types of cancer and rheumatoid arthritis. Learn about side effects, drug interactions, dosages, warnings, and more. Methotrexate tablet is used alone or together with other medicines to treat several types of cancer, such as breast, head and neck, lung, blood (eg, acute lymphoblastic leukemia or ALL), bone, lymph node (eg, mycosis fungoides, relapsed or refractory non-Hodgkin lymphoma), or uterus cancer. Overview: Methotrexate is used to treat certain types of arthritis, cancer, and severe psoriasis. Common side effects include nausea or vomiting, upset stomach, and mouth sores. Serious side. Methotrexate sodium is a type of chemotherapy called an antimetabolite, which is a drug that mimics a natural chemical and prevents its use in cells. It interferes with the way cells divide and function. Each methotrexate tablet contains 2.5 mg methotrexate equivalent to 2.74 mg methotrexate sodium and the following inactive ingredients: lactose monohydrate, magnesium stearate and microcrystalline cellulose. Methotrexate treats certain leukemias and lymphomas, mycosis fungoides, rheumatoid arthritis, polyarticular juvenile idiopathic arthritis in children, and severe psoriasis in adults. Learn about side effects, interactions, and indications. Methotrexate is a type of drug called an antimetabolite. It treats rheumatoid arthritis by decreasing the activity of your immune system, treats psoriasis by slowing the growth of skin cells and treats cancer by slowing the growth of cancer cells.