Methotrexate is widely regarded as one of the safest of all arthritis drugs, though it carries some potential downsides. Gastrointestinal symptoms such as nausea and vomiting are its most frequent side effects. Other possible side effects include hair loss, mouth sores, shortness of breath, headaches, fatigue, drowsiness and dizziness. Taking folic acid daily can help offset most side effects. Long-term use of cyclosporine, methotrexate, and nonsteroidal anti-inflammatory drugs, such as ibuprofen, can also lead to liver problems or liver failure. Outlook. RA can result in weight loss or. Methotrexate has rarely caused serious (sometimes fatal) side effects. Therefore, this medication should be used only to treat cancer or severe diseases caused by an overactive immune system (such. Methotrexate is indicated in the treatment of gestational choriocarcinoma, chorioadenoma destruens, and hydatidiform mole. In acute lymphocytic leukemia, methotrexate is indicated in the prophylaxis of meningeal leukemia and is used in maintenance therapy in combination with other chemotherapeutic agents. Methotrexate is also indicated in the treatment of meningeal leukemia. Methotrexate also stops some normal cells working properly, causing side effects. You might have another drug called folinic acid after methotrexate. It helps normal cells recover and reduces side effects. How you have methotrexate. How you have methotrexate depends on what type of cancer you have. You can have it as: an injection into your bloodstream (intravenous) a tablet or a liquid you. Methotrexate (brand name Methoblastin) is a medicine used to treat rheumatoid arthritis as well as other rheumatic conditions such as juvenile arthritis, lupus (also known as SLE), psoriatic arthritis and polymyositis (muscle inflammation). Methotrexate is an immunosuppressive medicine, and reduces inflammation in the joints and associated pain and swelling.