Methotrexate (Brand Name: Rheumatrex)

When is methotrexate used?

Methotrexate may be used to treat rheumatoid arthritis, juvenile idiopathic arthritis, uveitis, psoriasis and other rheumatic diseases.

Low-dose methotrexate has been widely used since the 1980s for the safe and effective treatment of arthritis.

Methotrexate may be considered chemotherapy as it is also used to treat cancer, although using doses 100 times that which is used to treat arthritis (e.g. 1,000-5,000mg intravenous infusion for cancer, rather than the lower doses used for arthritis 10-25mg).

How does it work?

Methotrexate is one of the classic DMARDs (disease-modifying-anti-rheumatic-drugs), in that its usage has been shown to treat the pain and swelling of arthritis and prevent joint damage and future disability.

Methotrexate works very well, and is comparable to many of the newer biologic medications (biologics) used to treat arthritis. Methotrexate acts by preventing cell growth, suppressing the immune system and the inflammation of arthritis.

The anti-inflammatory effect is likely due to methotrexate’s ability to change levels of adenosine, a chemical in the blood.

How is it given?

Methotrexate may be given as a weekly injection or by mouth as tablets or liquid. Tablets are usually 2.5mg, and the injectable form comes in a concentration of 25mg/ml. Dosage is calculated based on the weight of the child. One should take methotrexate on the same day each week.

Overall, children tolerate methotrexate very well, with very few side effects.

Possible side effects

  • Nausea, vomiting, stomach pain, diarrhea, mouth sores
  • Drowsiness, dizziness
  • Lower white blood cell count, increased risk of infection
  • Elevated liver function tests
  • May cause birth defects or miscarriages
  • Rash from sun exposure
  • Hair loss

Rare side effects

  • Liver disease (cirrhosis)
  • Lung disease
  • Bone marrow suppression
  • Bleeding

This is does not include all possible side effects of methotrexate.

Special instructions

  • It takes at least six weeks to see the full effect of methotrexate.
  • Your child's doctor may adjust the dose of methotrexate or change from oral to the injectable form depending upon the response.
  • Methotrexate can be taken with or without food.
  • Folic acid, vitamin B9, is always used to minimize the side effects of methotrexate. Folic acid should be taken every day, except the day of methotrexate.
  • One needs to check blood tests every 6-12 weeks to monitor for any toxicity.
  • Call your child's doctor if you have prolonged fever or are exposed to chickenpox.
  • NSAIDs such as ibuprofen (example: Advil) may be safely used with low-dose methotrexate (10-25mg).
  • Your child should not receive “live” vaccines, such as MMR, oral polio or Varicella.
  • Your child should have a PPD (tuberculosis skin test) placed and update all of your vaccinations (including Hepatitis B) prior to starting methotrexate.
  • Yearly flu shot is recommended.
  • Never skip doses.
  • Place the needles and syringes in a proper “sharps container."
  • Store methotrexate at room temperature away from light and moisture.

Call your child's doctor with any questions.