Methotrexate Guide: Uses, Dosing, Side Effects

About Methotrexate

Methotrexate is an antimetabolite or ‘cytotoxic’ medicine primarily used to treat conditions involving over-activity in the body, such as certain cancers, rheumatoid arthritis, and severe psoriasis. It functions as an immunosuppressant, slowing down the immune system to reduce inflammation and prevent flare-ups in autoimmune diseases. Available as tablets (e.g., 2.5mg and 10mg), oral liquid, pre-filled injection pens (Metoject), or injections under brands like Maxtrex, Jylamvo, Methofill, Nordimet, and Zlatal.

In rheumatoid arthritis, methotrexate addresses immune system over-activity that attacks joints, causing pain, swelling, and loss of function. It may take 3-6 weeks for initial improvement and up to 12 weeks or longer for full benefits. For psoriasis, it treats severe cases with red, scaly patches. It is also indicated for cancers like breast, lung, blood (acute lymphoblastic leukemia), and others, often combined with other therapies.

Key facts about Methotrexate

• Methotrexate is taken once a week for non-cancer conditions like rheumatoid arthritis, psoriasis, and Crohn’s disease, always on the same day.
• Patients receive a patient card or booklet to record weekly doses, blood test results, and monitoring details—keep it with you and show healthcare staff.
• It works slowly; full effects may take several weeks to months.
• Important: Tablets come in 2.5mg and 10mg strengths—never exceed the prescribed dose, as weekly dosing is critical to avoid toxicity.
• Regular blood tests are required to monitor liver function, blood counts, and adjust dosage.

How and when to take Methotrexate

Methotrexate dosage is individualized based on condition, response, and blood tests. For rheumatoid arthritis or psoriasis, start low (e.g., 7.5mg weekly) and titrate up to 25mg weekly, taken as a single dose or split over 24 hours. Cancer doses are higher and often daily or in cycles under hospital supervision.

• Tablets: Swallow with water, with or without food. If splitting doses, take second half 8-12 hours later.
• Injections (Metoject): Self-administer subcutaneously once weekly after training.
• Folic acid supplement: Often prescribed (e.g., 5mg 1-6 days/week, not on methotrexate day) to reduce side effects like nausea and mouth sores.
• Take at the same day and time weekly to maintain steady levels.

If you miss a dose, take it as soon as remembered unless near the next dose—do not double up. Contact your doctor for advice. Continue even if feeling well, as stopping abruptly can worsen symptoms.

Dosage information

Side effects of Methotrexate

Most people tolerate methotrexate well, but it can cause side effects due to immune suppression and effects on rapidly dividing cells. Common ones are mild and manageable with folic acid.

Common side effects

• Feeling sick (nausea), loss of appetite, stomach upset—take with food or anti-nausea meds.
• Mouth sores/ulcers—use folic acid, good oral hygiene.
• Fatigue, mild hair thinning.
• Raised liver enzymes (usually reversible with dose adjustment).

Serious side effects

Seek immediate medical help for:

• Infection signs: Sore throat, fever, chills—due to low white blood cells.
• Bleeding/bruising: Low platelets.
• Liver damage: Yellowing skin/eyes, dark urine (long-term risk).
• Lung problems: Dry cough, shortness of breath.
• Severe allergic reaction: Rash, swelling, breathing difficulty.

Immediate side effects (within 48 hours) include nausea persisting after doses—inform your doctor. Long-term: Monitor for fibrosis or malignancy risk.

How to cope with side effects

• Nausea: Take with evening meal, use folic acid, sip ginger tea.
• Mouth sores: Avoid spicy/acidic foods, use alcohol-free mouthwash, saline rinses.
• Fatigue: Pace activities, ensure rest.
• Infection prevention: Avoid unwell people, practice hand hygiene, ensure vaccinations are up-to-date (avoid live vaccines).
• Regular blood tests every 1-3 months once stable.

Cautions of Methotrexate

Methotrexate is contraindicated in pregnancy, breastfeeding, alcoholism, severe liver/kidney disease, or active infections.

• Pregnancy/contraception: Highly teratogenic—use effective contraception during and 6 months after (men) or 3 months (women). Inform doctor if pregnant.
• Alcohol: Avoid completely—raises liver toxicity risk.
• Other meds: Avoid NSAIDs (e.g., ibuprofen) without advice; interacts with antibiotics, trimethoprim.
• Vaccines: No live vaccines (e.g., yellow fever); check others.
• Driving: Usually safe unless side effects like dizziness occur.

Serious allergic reaction

Rare but call emergency services for difficulty breathing, swelling, or widespread rash.

Pregnancy and breastfeeding

Do not use in pregnancy—causes birth defects. Stop 6 months before conceiving (men) or 3 months (women). Not recommended breastfeeding.

Monitoring and tests

Baseline and regular blood tests for full blood count, liver/kidney function every 1-2 weeks initially, then 2-3 months. Chest X-ray if lung symptoms.

Common questions about Methotrexate

Why take folic acid with methotrexate?

Folic acid reduces side effects like nausea and mouth sores without reducing efficacy.

Is methotrexate a painkiller?

No, it treats underlying inflammation but not acute pain—use paracetamol if needed.

How long until it works?

3-12 weeks for benefits in arthritis/psoriasis.

Can I drink alcohol?

No, avoid to protect liver.

What if I miss a dose?

Take soon as remembered; don’t double.

Alternatives to Methotrexate

• Other DMARDs: Leflunomide, sulfasalazine for RA.
• Biologics: Adalimumab, etanercept if methotrexate inadequate.
• Topicals/phototherapy for milder psoriasis.

Sneha Tete

Health Writer