Methotrexate
How this therapy is used at Arthritis Care of Texas in Corpus Christi, TX — what it is, how it is taken, side effects, and safety checks.
- Treats
- Rheumatoid arthritis · Psoriatic arthritis · Vasculitis
- How given
- Pill, or weekly self-injection
- How often
- Once weekly
Methotrexate is a disease-controlling treatment: it prevents joint damage and disability rather than just masking pain. It takes 3–12 weeks to start working and keeps protecting only while taken weekly. It is not a painkiller — pain relief follows as inflammation is controlled. Never judge it in the first fortnight.
What it is: A disease-modifying anti-rheumatic drug (DMARD) that dampens an overactive immune system to limit or prevent joint damage and disability, rather than just treating symptoms. It is a long-term treatment — benefits may take 3–12 weeks. Keep taking it even if it is slow to work, and even when you improve. It is prescribed for rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis, and vasculitis (and is also used in much higher doses for some cancers).
How it's taken: Tablets once weekly, on the same day, swallowed whole. Use the 2.5 mg tablets only — the 2.5 mg and 10 mg tablets are similar in colour, so always check the dose. The starting dose is 7.5–15 mg weekly, which may increase to a maximum of about 25 mg weekly. Alternatively, a weekly injection under the skin can be used if tablets cause side effects. Folic acid tablets are usually prescribed alongside — they reduce side effects, and some doctors advise not taking folic acid on methotrexate day.
Side effects: Nausea, vomiting, diarrhoea, mouth ulcers, minor hair loss, and skin rashes. It can affect blood counts and the liver — blood tests are done before starting and regularly during treatment (you must not take methotrexate unless you're having regular blood checks — every 2 weeks while building the dose, then every 6 weeks on a stable dose). A chest X-ray is done before starting, as it can affect the lungs; it is not suitable with long-term lung disease such as fibrosis or emphysema. Report promptly: sore throat, fever, infection signs, shortness of breath, unexplained bruising or bleeding, and jaundice. Stop and see a doctor immediately if severe. Rarely, lung inflammation with breathlessness can occur. Chickenpox and shingles can be severe.
Interactions: Some antibiotics interact (trimethoprim and septrin — avoid them; you may need to pause methotrexate during antibiotic courses). Avoid phenytoin and theophylline — discuss with your team first, don't just stop. Check with your doctor before starting new medicines.
Pregnancy: Methotrexate may harm the baby if taken during pregnancy. Women should use contraception, continue it for at least 3 months after stopping before trying for a baby, and stop and see a doctor as soon as possible if pregnancy occurs. For men, current guidelines say there is no need to stop when trying to father a baby. Do not breastfeed on methotrexate — it passes into milk and its effects are uncertain.
Why the checks: Nothing here is routine for its own sake: blood tests monitor the liver and blood counts because methotrexate can affect both without symptoms, and the schedule (frequent while the dose builds, spaced once stable) matches when changes actually occur; the pre-treatment chest X-ray gives a baseline because the drug can, uncommonly, affect the lungs; and folic acid is prescribed because it measurably reduces side effects while the methotrexate does its work.
Used for Rheumatoid arthritis · Psoriatic arthritis · Vasculitis
Common worries
Is methotrexate chemotherapy?
It was first developed for cancer — at doses many times higher, given daily. For arthritis we use a much lower dose, once a week, where it works as an immune-calming drug, not chemotherapy. The weekly rhythm is the whole point: daily dosing would be dangerous, which is why we are emphatic about ‘once a week, same day’.
Why all the blood tests?
Methotrexate is processed by the liver and can affect blood counts — silently. Regular tests (every 2 weeks while the dose builds, then about every 6 weeks) catch any change while it is trivial to fix. Feeling well does not replace them; the tests are a condition of safe treatment.
Will I lose my hair / feel sick every week?
Some nausea or tiredness the day after the dose is common at first and usually eases; folic acid, prescribed alongside, reduces it. Mild hair thinning can occur but significant loss is uncommon at these doses. If side effects persist, tell us — switching to the injection form often solves them.
Ready to be seen? New patients are seen within 2–4 weeks.