It is also used by rheumatologists for other rheumatic diseases, including juvenile arthritis and psoriatic arthritis. It is not ordinarily prescribed until other forms of anti-inflammatory treatment have proven inadequate. It should only be prescribed by physicians who are experienced in initiating and monitoring such antirheumatic therapy. The drug is appropriate therapy for selected people with rheumatoid arthritis. Clinical studies with methotrexate have demonstrated that a majority of people who take the drug have less joint pain and swelling, reduced morning stiffness, less fatigue, improvement in functional status, and a slowing of the rate of radiographic progression.
Improvement usually occurs between three and six weeks after treatment is initiated.
The dosage averages between 7.5 and 25 mg. The most common side effects of methotrexate include loss of appetite, nausea, diarrhea, sores or ulcers in the mouth, hair loss, and decreases in the platelets, white blood cell or red blood cell counts. Potential for liver toxicity exists, specifically in people with preexisting liver disease or who are heavy users of alcohol. Rare but serious side effects include fibrosis and cirrhosis of the liver, bone marrow suppression, a reaction similar to pneumonia, usually indicated by fever, cough and severe shortness of breath, and rarely, lymphoma which may resolves with discontinuation. Folic acid and folinic acid can be used to reduce many of the side effects.