Methotrexate is a medication used to treat a variety of medical conditions, primarily autoimmune diseases and certain types of cancer. It is a versatile drug with a wide range of applications, and it can be taken orally, injected into a muscle, or given intravenously, depending on the condition being treated.

Here are some key uses and information about methotrexate:

1. Cancer Treatment: Methotrexate is commonly used in the treatment of certain types of cancer, including leukemia, lymphoma, and gestational trophoblastic neoplasia. It works by interfering with the growth of cancer cells.

2. Rheumatoid Arthritis: Methotrexate is a cornerstone medication for the treatment of rheumatoid arthritis, an autoimmune disease that causes joint inflammation and pain. It helps reduce joint damage and control symptoms.

3. Psoriasis: This drug can also be used to treat severe psoriasis, a chronic skin condition characterized by red, scaly patches. Methotrexate helps to slow the growth of skin cells and reduce inflammation.

4. Inflammatory Bowel Disease (IBD): Methotrexate may be prescribed for individuals with Crohn's disease or ulcerative colitis, two forms of IBD, when other treatments have been ineffective.

5. Ectopic Pregnancy: In some cases of ectopic pregnancy (when a fertilized egg implants outside the uterus), methotrexate can be used to terminate the pregnancy to prevent lifethreatening complications.

6. Dosage: The dosage of methotrexate varies depending on the condition being treated and the individual's response. It is usually taken once a week. It's crucial to follow the prescribed dosage and schedule carefully.

7. Side Effects: Methotrexate can cause a range of side effects, including nausea, vomiting, fatigue, mouth sores, and liver abnormalities. Regular monitoring of liver function and blood cell counts is necessary while on this medication.

8. Contraindications: Methotrexate is not suitable for everyone. It should be avoided during pregnancy, as it can cause birth defects. People with certain medical conditions, such as severe liver or kidney disease, may not be candidates for this medication.

9. Interaction with Other Medications: Methotrexate can interact with other drugs, including some antibiotics and nonsteroidal antiinflammatory drugs (NSAIDs). It's important to inform your healthcare provider of all medications you are taking to avoid potential interactions.

10. Folate Supplementation: To mitigate some of the side effects of methotrexate, such as mouth sores and nausea, folate (a B vitamin) supplements are often prescribed. These supplements help counteract the effects of methotrexate on normal, healthy cells.

11. Regular Monitoring: When taking methotrexate, regular blood tests are essential to monitor your liver function, blood cell counts, and overall health.

Methotrexate is a potent medication with the potential for both significant benefits and side effects. It should only be used under the supervision of a qualified healthcare professional who can carefully monitor its effects and adjust the treatment plan as needed. Patients prescribed methotrexate should also receive counseling on its potential risks and benefits.