Methotrexate contains methotrexate, a disease-modifying medicine used to treat autoimmune conditions, inflammatory disorders, and certain cancers. It is commonly prescribed in low weekly doses for conditions such as rheumatoid arthritis and psoriasis, where the immune system causes inflammation and tissue damage. Methotrexate works by slowing abnormal immune activity and reducing inflammation. Methotrexate may be used alone or in combination with other therapies depending on disease severity and treatment goals.

Methotrexate contains methotrexate, an antimetabolite and folate antagonist widely used in rheumatology, dermatology, and oncology. In low weekly doses, it is considered a cornerstone treatment for autoimmune and inflammatory diseases such as rheumatoid arthritis, psoriatic arthritis, and severe psoriasis. In higher doses, methotrexate is also used in selected cancer treatment protocols under specialist supervision.

Methotrexate works by inhibiting dihydrofolate reductase, an enzyme involved in folate metabolism and DNA synthesis. This action slows the activity of rapidly dividing cells and suppresses overactive immune responses that drive chronic inflammation.

In autoimmune diseases, methotrexate helps reduce joint swelling, pain, stiffness, and long-term tissue damage. In psoriasis, it helps control excessive skin cell turnover and inflammatory plaques. Regular weekly use improves symptoms gradually, often requiring several weeks before full benefit is seen.

Because methotrexate affects folate metabolism, folic acid supplementation is commonly prescribed alongside treatment to reduce side effects such as mouth ulcers, nausea, and liver irritation.

The medicine is metabolised in the liver and primarily eliminated through the kidneys, so patients with kidney impairment, liver disease, or blood disorders require close monitoring. Blood tests are routinely needed to assess liver function, kidney function, and blood counts during treatment. When taken exactly as prescribed, Methotrexate is an effective long-term therapy for controlling chronic inflammatory disease and preventing progression.

Rheumatoid Arthritis

Used to reduce joint inflammation, stiffness, and long-term joint damage.

Psoriasis

Prescribed in severe psoriasis when topical treatments are insufficient.

Psoriatic Arthritis

Helps reduce inflammation affecting joints and skin.

Certain Cancers

Used in selected oncology protocols under specialist care.

Other Autoimmune Conditions

May be used in selected inflammatory diseases depending on clinical need.

Disease-Modifying Effect

Helps slow progression of inflammatory diseases rather than only treating symptoms.

Reduces Joint Damage

In rheumatoid arthritis, early treatment helps preserve joint structure and function.

Controls Chronic Inflammation

Reduces pain, swelling, and morning stiffness in autoimmune conditions.

Improves Skin Symptoms

In psoriasis, helps reduce plaque thickness and scaling.

Long-Term Disease Control

Supports sustained remission when used consistently.

Steroid-Sparing Effect

May reduce the need for long-term corticosteroid use.

Broad Clinical Utility

Used across rheumatology, dermatology, and oncology settings.

When taken as directed, Methotrexate is effective but requires monitoring because side effects can affect blood cells, liver, and the digestive system.

Common Side Effects

• Nausea and Loss of Appetite: Mild digestive discomfort may occur after weekly dosing.

• Mouth Ulcers: Folate depletion can lead to soreness or ulcers in the mouth.

• Fatigue: A tired feeling may occur after the weekly dose.

Uncommon Side Effects

• Mild Hair Thinning: Temporary hair loss may occur in some patients.

• Liver Enzyme Elevation: Liver blood tests may show changes requiring monitoring.

• Diarrhoea or Abdominal Discomfort: Mild gastrointestinal upset may occur.

Serious Side Effects (Require Immediate Medical Attention)

• Bone Marrow Suppression: Unusual bruising, infection, or bleeding may indicate low blood counts.

• Severe Liver Toxicity: Persistent nausea, jaundice, or abdominal pain requires urgent evaluation.

• Breathing Problems: Persistent dry cough or shortness of breath may indicate lung toxicity.

• Severe Allergic Reactions: Rash, swelling, or difficulty breathing requires immediate care.

Methotrexate should be taken exactly as prescribed by your physician. It is usually taken once weekly, not daily, which is extremely important for safety. The dose is taken on the same day each week. Tablets may be taken with water, with or without food. Folic acid is often prescribed on a separate day to reduce side effects. Swallow the tablet whole and follow the exact weekly schedule advised by your doctor.

The mechanism of Methotrexate is based on inhibition of dihydrofolate reductase, an enzyme essential for folate metabolism and DNA synthesis.

By reducing folate availability, methotrexate interferes with DNA replication in rapidly dividing cells. In autoimmune disease, this suppresses overactive immune cell activity and lowers inflammatory mediator production.

Methotrexate also increases extracellular adenosine, an anti-inflammatory mediator that helps reduce joint inflammation and tissue injury. This dual effect, folate antagonism and immune regulation, explains its effectiveness in inflammatory disorders.

Because immune and blood cells are affected, regular monitoring is essential throughout therapy.

• Weekly Dosing Only: Methotrexate must be taken once weekly unless specifically prescribed otherwise.

• Do Not Self-Adjust Dose: Never increase or repeat doses without medical advice.

• Regular Blood Monitoring: Liver function, kidney function, and blood counts must be checked routinely.

• Take Folic Acid as Prescribed: Helps reduce mouth ulcers and digestive side effects.

• Watch for Infection: Report fever, sore throat, or unusual weakness promptly.

• Avoid Pregnancy: Both men and women may require contraception during and after treatment.

• Protect the Liver: Limit alcohol and avoid unnecessary hepatotoxic medicines.

While Methotrexate can be taken with or without food, certain dietary factors may influence its effectiveness and safety.

• Alcohol (High): Alcohol significantly increases liver toxicity risk. Avoid or strictly limit intake.

• Folate-Rich Foods (Low): Normal dietary folate is safe, but folic acid supplements should follow medical guidance.

• Caffeine (Moderate): Excessive caffeine may reduce methotrexate response in some patients.

• High-Fat Meals (Low): May delay absorption slightly but usually not clinically significant.

• Unpasteurised Foods (Moderate): Because immunity may be reduced, infection risk should be minimised.

Methotrexate can interact with medicines affecting kidney clearance, blood counts, or liver metabolism.

• NSAIDs (Moderate-High): Ibuprofen and similar drugs may reduce methotrexate clearance and increase toxicity.

• Other Immunosuppressants (High): Increases infection and blood toxicity risk.

• Antibiotics (Moderate): Trimethoprim and sulfonamides may increase toxicity.

• Proton Pump Inhibitors (Moderate): May affect methotrexate elimination in some cases.

• Live Vaccines (High): Should usually be avoided during therapy.

• Leflunomide (High): Combined use increases liver toxicity risk.

Methotrexate should be used carefully in patients with certain medical conditions due to immune suppression and organ toxicity.

• Liver Disease (High): Increased risk of severe liver injury.

• Kidney Disease (High): Reduced clearance may increase toxicity.

• Bone Marrow Disorders (High): Blood count suppression may worsen.

• Active Infection (High): Immunosuppression may worsen infection severity.

• Lung Disease (Moderate): Rare methotrexate lung toxicity requires caution.

• Peptic Ulcer Disease (Moderate): Gastrointestinal irritation may worsen symptoms.

If you miss your weekly dose, take it as soon as you remember within 1–2 days if advised by your doctor. If it is nearly time for your next weekly dose, skip the missed one and continue with your normal schedule. Do not take extra tablets or double doses, as methotrexate overdose can be dangerous.