About methotrexate
Antimetabolite immunosuppressant and chemotherapy drug
Used for
- Treats certain cancers, including leukemia, lymphoma, and osteosarcoma.
- Treats severe psoriasis and rheumatoid arthritis.
- Treats ectopic pregnancy in selected cases.
Usual adult dose
Highly condition-specific; cancer doses vary widely. Rheumatoid arthritis often starts at 7.5 mg once weekly, adjusted by a specialist.
Usual dose in children
Cancer dosing is calculated by body size and treatment protocol; specialist supervision is essential.
Common side effects
- Nausea, vomiting, mouth sores, and diarrhea.
- Low blood-cell counts, increasing infection or bleeding risk.
- Liver injury and kidney problems.
- Lung inflammation, rash, or hair loss.
Important warnings
- For non-cancer conditions, dosing is usually weekly, not daily; daily errors can be fatal.
- Can cause severe birth defects and pregnancy loss; avoid during pregnancy for most uses.
- Requires blood-count, liver, and kidney monitoring.
- Seek urgent care for severe infection, unusual bleeding, breathing difficulty, or serious allergic symptoms.
Pregnancy
Can cause fetal harm or pregnancy loss; generally contraindicated for non-cancer treatment during pregnancy. Cancer use requires specialist assessment.
Breastfeeding
Generally not recommended during treatment; timing to resume depends on dose and clinical guidance.
Interactions
- Trimethoprim or co-trimoxazole can increase bone-marrow toxicity.
- NSAIDs and some penicillins can increase methotrexate toxicity, especially with high doses or kidney impairment.
- Live vaccines may increase infection risk.
- Alcohol and other liver-toxic medicines can increase liver injury risk.
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 It may be incomplete or out of date.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.