About methotrex ate
Antimetabolite; folate antagonist
Used for
- Rheumatoid arthritis and other inflammatory conditions
- Severe psoriasis
- Certain cancers, including leukemia and lymphoma
Usual adult dose
Varies by condition. In inflammatory diseases, commonly 7.5–25 mg once weekly; cancer doses vary widely.
Usual dose in children
Specialist-set doses for some cancers and juvenile arthritis; varies by condition and body size.
Common side effects
- Nausea, vomiting, mouth sores, diarrhea
- Low blood cell counts and increased infection risk
- Liver injury
- Lung inflammation
Important warnings
- Take once weekly, never daily, for inflammatory diseases; daily use can be fatal.
- Requires regular blood tests and monitoring of liver, kidneys, and blood counts.
- Avoid or use only with specialist oversight in significant liver or kidney disease.
- Seek urgent care for severe infection, breathing problems, unusual bleeding, or severe skin reactions.
Pregnancy
Can cause miscarriage and serious birth defects. Avoid during pregnancy; planning and washout timing require specialist guidance.
Breastfeeding
Usually avoided; limited specialist-supervised use may be possible with low weekly doses and a defined interruption period.
Interactions
- Trimethoprim or co-trimoxazole can increase bone marrow toxicity.
- NSAIDs and some antibiotics can increase toxicity, especially with impaired kidney function.
- Other medicines that affect the liver or immune system may increase harm.
- Folic acid can reduce some side effects; timing and dose should be clinician-directed.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.