Methotrexate is a medication commonly used in the treatment of cancer, autoimmune diseases, and certain types of arthritis. It works by inhibiting the growth of rapidly dividing cells, such as cancer cells or those involved in inflammation. Methotrexate is considered a disease-modifying anti-rheumatic drug (DMARD) for arthritis and is often used in combination with other medications to control symptoms and slow disease progression. Methotrexate can be taken orally, by injection, or intravenously, depending on the condition being treated. Common side effects of methotrexate include nausea, fatigue, and an increased risk of infection due to its effects on the immune system. Regular monitoring of blood counts and liver function is typically required while taking methotrexate to ensure its safety and effectiveness. Overall, methotrexate is a widely used and effective medication for managing various medical conditions, but it must be carefully monitored and managed by a healthcare provider to minimize potential side effects.