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Methotrexate

Medication antimetabolite DMARD / immunosuppressant other
Aka: Trexall
Brands seen in Singapore: Merex, Methotrexate Remedica, Emthexate, DBL Methotrexate, Methotrexate Orion
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Autoimmune conditions such as rheumatoid arthritis
When to take
HealthHub: benefit begins after 6 weeks, full by 12 weeks
Take with
Tablets with or after food · once weekly, not daily
Pros & cons
Pros
  • HealthHub: a disease modifying drug in arthritis
  • HealthHub: reduces pain, swelling and joint damage
  • Folate is often given alongside to cut side effects
Cons
  • Weekly dosing — daily use by mistake can be fatal
  • Mouth ulcers, nausea and hair thinning are common
  • Not in pregnancy — miscarriage and birth defects
Sources
  1. HSA — Listing of Registered Therapeutic Products (data.gov.sg d_767279312753558cbf19d48344577084), Forensicclassification column; cached at /tmp/hsa_all.json and filtered locally, not re-fetched · read 2026-08-27
    what it says
    “MEREX 2.5-METHOTREXATE SIN16737P · METHOTREXATE REMEDICA SIN17136P · METHOTREXATE TABLET 2.5 mg SIN00260P · EMTHEXATE 2.5 SIN12414P · DBL METHOTREXATE INJECTION SIN00242P/SIN00758P · METHOTREXATE ORION SIN16395P — all 7 rows 'Prescription Only'”
  2. MOH National Drug Formulary (Singapore) — METHOTREXATE ORION TABLETS 2.5 MG [SIN16395P], product information · read 2026-08-27
    what it says
    “METHOTREXATE ORION TABLETS 2.5 MG [SIN16395P] … METHOTREXATE DISODIUM EQV METHOTREXATE - 2.5 MG … Forensic Classification PRESCRIPTION ONLY MEDICINES … ATC code L01BA01 … Prescription-only Medicines with Exemptions for Supply without Prescription NA”
  3. MOH National Drug Formulary (Singapore) — METHOTREXATE ORION [SIN16395P], Dosage and Administration: psoriasis ceilings · read 2026-08-27
    what it says
    “(1) Weekly single dose schedule: 10 to 25 mg orally per week until adequate response is achieved. Weekly dosage should not exceed 50 mg. … Daily dosage should not exceed 6.25 mg.”
  4. MOH National Drug Formulary (Singapore) — METHOTREXATE ORION [SIN16395P], Dosage and Administration: rheumatoid arthritis ceiling · read 2026-08-27
    what it says
    “dosage may be gradually increased further to achieve optimal response, but not ordinarily to exceed a total weekly dosage of 20mg”
  5. MOH National Drug Formulary (Singapore) — METHOTREXATE ORION [SIN16395P], Dosage and Administration: weekly-regimen warning · read 2026-08-27
    what it says
    “Both the doctor and the pharmacist should emphasise to the patient the importance of the weekly dosage regimens: mistaken daily use may cause serious and sometimes life threatening or fatal toxicity.”
  6. HealthHub (MOH Singapore) — Methotrexate, medication information leaflet, last reviewed 12 June 2023 · read 2026-08-27
    what it says
    “Methotrexate is a medicine that reduces over-activity of the immune system. It is used to treat various autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus (SLE), juvenile idiopathic arthritis, psoriasis, psoriatic arthritis, uveitis, and inflammatory myositis (muscle inflammation).”
  7. HealthHub (MOH Singapore) — Methotrexate, role in arthritis · read 2026-08-27
    what it says
    “In arthritis, methotrexate acts as a disease modifying anti-rheumatic drug (DMARD) that helps to reduce pain, swelling, and long-term joint damage.”
  8. HealthHub (MOH Singapore) — Methotrexate, how to take it and onset · read 2026-08-27
    what it says
    “Tablets should be taken with or after food. … The beneficial effects of methotrexate will begin after 6 weeks and the full benefits may not be seen until after 12 weeks of treatment.”
  9. HealthHub (MOH Singapore) — Methotrexate, typical weekly dose · read 2026-08-27
    what it says
    “A typical weekly dose of methotrexate ranges from 7.5mg to 25mg, given in the form of tablets or injection. Dosage may vary depending on your disease activity and response to the medicine.”
  10. HealthHub (MOH Singapore) — Methotrexate, folic or folinic acid · read 2026-08-27
    what it says
    “Folic or folinic acid (also called folate) is often given to reduce the risk of some side effects. It is usually taken a day before or after methotrexate unless advised otherwise by your doctor.”
  11. HealthHub (MOH Singapore) — Methotrexate, common and serious side effects · read 2026-08-27
    what it says
    “Mouth ulcers … Nausea, vomiting, diarrhoea or loss of appetite … Slow loss of hair … Skin rashes … Lung inflammation (Warning signs: Persistent coughing, breathlessness or chest pain) … Liver disorder … Blood disorders”
  12. HealthHub (MOH Singapore) — Methotrexate, precautions: conception and breastfeeding · read 2026-08-27
    what it says
    “methotrexate can cause miscarriage and serious birth defects, and should be avoided before conceiving and during pregnancy … Patients should also wait at least three months after stopping methotrexate before trying for a child.”
  13. HealthHub (MOH Singapore) — Methotrexate, food and medication to avoid · read 2026-08-27
    what it says
    “Avoid live vaccines such as MMR (measles, mumps and rubella), OPV (oral polio vaccine), yellow fever or BCG (tuberculosis) … Do not drink alcohol while on this medicine as it may increase the risk of liver toxicity”
  14. NHS medicines A–Z — Taking methotrexate with other medicines and herbal supplements (reviewed 14 March 2023) · read 2026-08-27
    what it says
    “Tell your doctor if you're taking any of these medicines … non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen … co-trimoxazole, trimethoprim or other antibiotics … medicines that make you pee more (diuretics) … medicines used to treat indigestion, such as omeprazole”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.