Methotrexate
Also sold as: Folitrax
Usual adult dose
Dose is set by your specialist. For arthritis it is taken ONCE A WEEK (usually 7.5 to 25 mg on the same day each week) — never every day. Folic acid is usually given on another day. Regular blood tests are needed.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- nausea
- tiredness
- mouth ulcers
- mild hair loss
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- sore throat
- fever or signs of infection
- unusual bleeding or bruising
- new cough or shortness of breath
- yellow eyes or skin
Do not take it, or take care, if
- Pregnancy or planning pregnancy (men and women should use contraception during and for months after treatment)
- Breastfeeding
- Serious liver or kidney disease, or heavy alcohol use
- Active serious infection or low blood counts
Interactions
Medicines that can react with this one.
Serious4 medicinesDo not take these together unless your doctor says so.
- Co-trimoxazole
Co-trimoxazole with methotrexate can cause severe bone marrow damage; avoid together.
- Diclofenac
Can raise methotrexate levels and cause serious toxicity.
- Metamizole
Both can lower blood cell counts; using them together raises the risk of serious blood problems.
- Sulfadoxine + Pyrimethamine
Both block folate; together they can cause serious bone marrow damage.
Moderate10 medicinesTake together only with care. Ask your doctor or pharmacist.
- Amoxicillin
Can reduce methotrexate clearance and raise its toxicity.
- Amoxicillin + Clavulanic acid
Can reduce methotrexate clearance and raise its toxicity.
- Aspirin
Aspirin can raise methotrexate levels and toxicity.
- Benzylpenicillin
Penicillins can reduce methotrexate clearance and raise its toxicity.
- Esomeprazole
Can raise methotrexate levels, especially with high doses.
- Ibuprofen
NSAIDs can raise methotrexate levels; use only with the doctor agreeing and blood tests.
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- Lansoprazole
Can raise methotrexate levels, especially with high doses.
- Omeprazole
Can raise methotrexate levels, especially with high doses.
- Pantoprazole
Can raise methotrexate levels, especially with high doses.
- Phenoxymethylpenicillin
Penicillins can reduce methotrexate clearance and raise its toxicity.