Methotrexate: what it does, how to use it safely
Methotrexate is a medicine that treats inflammatory diseases like rheumatoid arthritis and psoriasis, and it’s also used in certain cancer regimens. It works by slowing down rapidly dividing cells and changing how the immune system behaves. That power helps many people, but it also means methotrexate needs careful handling—correct dose, regular tests, and clear safety steps.
How methotrexate is used and dosed
For autoimmune problems (RA, psoriasis) doctors usually give low doses once a week. Typical ranges are about 7.5–25 mg once weekly—either by mouth or as a subcutaneous injection. For cancer, doses and schedules are different and often much higher, with extra medicines (like leucovorin) to protect healthy cells. Never change the dose or frequency on your own: taking methotrexate daily instead of weekly can cause serious harm.
Practical tip: pick one day of the week for your dose and set a recurring reminder on your phone. If you forget a weekly dose, call your prescriber or pharmacist rather than double-dosing.
Safety and monitoring: what to watch for
Before starting, your provider will usually order baseline blood tests: full blood count, liver tests, and kidney function. Expect repeat tests often at first (every 2–4 weeks) and then less often once stable (every 1–3 months). These checks catch problems early—like low blood counts or liver changes—before they become dangerous.
Common side effects include nausea, mouth sores, and mild hair thinning. More serious signs that need urgent attention are unexplained bruising, persistent fever, shortness of breath or cough, yellowing skin/eyes, or severe stomach pain. If any of those happen, get medical help right away.
Folic acid is commonly prescribed alongside methotrexate to reduce mouth sores, nausea, and some blood-test abnormalities. Your prescriber will tell you the dose and timing—follow their plan. Also avoid alcohol or keep it very low; alcohol increases liver risk while on methotrexate.
Drug interactions matter. Don’t start new medicines, supplements, or herbal remedies without checking. Some antibiotics (like trimethoprim/sulfamethoxazole), certain painkillers, and high-dose NSAIDs can change how methotrexate behaves. Live vaccines are generally not advised while on methotrexate—ask your clinician about timing.
Pregnancy and breastfeeding: methotrexate can cause birth defects. People planning pregnancy should discuss stopping methotrexate with their doctor well in advance. Both partners may be advised to wait a period after stopping before trying to conceive.
Buying meds online? Only use reputable pharmacies that require a prescription and show clear contact details. Keep a copy of your prescription, carry a note about methotrexate use when traveling, and bring recent lab results if you’ll see a different provider.
If you have questions or new symptoms, contact your healthcare team. Methotrexate helps a lot of people, but using it safely means following the dose, getting regular blood tests, and watching for warning signs.
