Drug class · Joints & ligaments
Antimetabolite DMARDs
Antimetabolite DMARDs are a group of disease-modifying medicines; methotrexate is the member covered on this site. Methotrexate is an immunosuppressant used for inflammatory conditions such as rheumatoid arthritis, psoriasis and Crohn's disease, and sometimes for cancer. The NHS says it calms the immune system and helps reduce inflammation.
Mechanism of action
Methotrexate blocks an enzyme called dihydrofolate reductase, which the body uses to make tetrahydrofolate, a form of folate needed to build DNA and RNA. In inflammatory conditions, how low-dose methotrexate works is less clear.
Members of the class
Members with a page on this site are linked.
Conditions treated
Cautions
- Taking it daily by mistake instead of weekly has caused overdoses that were sometimes fatal.
- The MHRA introduced new measures in 2020 to reduce this risk, including a patient card for oral products.
- Regular blood tests are used to monitor treatment.
- The NHS says methotrexate is not recommended in pregnancy because it can cause birth defects.
Class warnings
- Taking it daily by mistake instead of weekly has caused overdoses that were sometimes fatal. UK
Class interactions
| With | Effect | Source |
|---|---|---|
| NSAIDs such as ibuprofen, aspirin and naproxen | NSAIDs can increase the risk of methotrexate toxicity, so they are used only on specialist advice. | UK |
| Trimethoprim and co-trimoxazole | Trimethoprim and co-trimoxazole are advised against because of the risk of severe bone marrow suppression. | UK |
| Live vaccines | Live vaccines are not recommended during treatment. | UK |
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Connected pages in detail
What each linked page on Anatomy Nexus covers, in a line, for Antimetabolite DMARDs.
Conditions
- Inflammatory bowel disease Chronic inflammation of the gut driven by an abnormal immune response: ulcerative colitis affects the colon's lining continuously from the rectum.
- Rheumatoid arthritis A chronic autoimmune disease in which the immune system attacks the synovial lining of joints.
Medications
- Methotrexate Methotrexate is an immunosuppressant used for inflammatory conditions such as rheumatoid arthritis, psoriasis and Crohn's disease.
Educational content. A drug class page describes what a family of medicines has in common. Individual medicines differ in dose, licensing and interactions; treatment choices belong to a prescriber.