Methotrexate is an immunosuppressant medication used to reduce reliance on steroids in various inflammatory and autoimmune conditions affecting the visual system. For autoimmune indications it is dosed once a week, never daily.

Critical safety: methotrexate is dosed ONCE WEEKLY for autoimmune disease

Daily dosing - even by accident, even for a few days - has caused fatal toxicity. The Institute for Safe Medication Practices (ISMP) lists methotrexate as a high-alert medication for this reason.

  • Confirm the day of the week with your prescriber and write it on the bottle.
  • Never "catch up" a missed dose without calling your prescriber.
  • If you accidentally take methotrexate on more than one day in a week, call your prescriber or poison control immediately - do not wait for symptoms.

FDA Boxed Warnings - methotrexate

The FDA label for methotrexate carries boxed warnings for:

  • Embryo-fetal toxicity - methotrexate causes miscarriage and major birth defects (see Pregnancy section).
  • Severe bone marrow suppression - life-threatening cytopenias can occur, especially with kidney impairment.
  • Hepatotoxicity - risk of cirrhosis with long-term use; alcohol greatly increases this risk.
  • Pulmonary toxicity - interstitial pneumonitis can develop acutely or chronically and can be fatal. Report any new cough or shortness of breath.
  • Serious infection - including opportunistic infections.
  • Renal toxicity and tumor lysis at high doses (oncology dosing); plus severe skin reactions, GI toxicity, and lymphoma.

Key takeaways

  • Dosed once weekly - never daily - for autoimmune disease
  • Steroid-sparing immunosuppressant that builds effect over weeks
  • Multiple FDA boxed warnings including hepatotoxicity, pneumonitis, and embryo-fetal toxicity
  • Folic acid supplementation reduces side effects
  • Contraindicated in pregnancy for autoimmune disease; contraception and conception plans need review for both female and male patients
  • Regular CBC, LFTs, and renal function monitoring is required

Questions about your diagnosis? Contact our office

Use for inflammatory eye disease is off-label. A primary trial supporting steroid-sparing treatment in noninfectious uveitis is listed below.

Common Uses

How It Works

  • Inhibits folic acid metabolism
  • Reduces immune cell activity
  • Anti-inflammatory effects
  • Effects build over weeks to months

Dosing

Important

  • Once weekly dosing (NOT daily)
  • Starting: 7.5-15 mg weekly
  • May increase to 25 mg weekly; the FAST uveitis trial used 25 mg/week under specialist monitoring
  • Oral or injectable

Folic Acid

  • Follow the prescribed folic-acid schedule; regimens differ
  • Folic acid reduces side effects
  • Ask which days to take it rather than assuming every patient skips methotrexate day

Side Effects

Common

  • Nausea (especially on dosing day)
  • Fatigue
  • Mouth sores
  • Hair thinning

Serious

  • Liver damage
  • Bone marrow suppression
  • Lung problems
  • Infection risk

Precautions

Pregnancy and contraception - methotrexate is teratogenic

Methotrexate can cause miscarriage and severe birth defects. The FDA label and specialist guidance differ for paternal exposure, so arrange a written conception plan with the prescribing team.

  • Women: the current FDA label recommends reliable contraception during treatment and for 6 months after the final dose. The 2020 ACR guideline recommends stopping before conception, typically 1-3 months beforehand for low-dose autoimmune use. Discuss how to apply the label and specialist guidance to your situation.
  • Men: the FDA label recommends stopping methotrexate at least 3 months before attempting to conceive. The 2020 ACR Reproductive Health Guideline now conditionally permits men to continue methotrexate during conception attempts based on more recent paternal-exposure safety data - discuss the right approach with your prescriber.
  • If you think you may be pregnant on methotrexate, contact your doctor the same day for a coordinated treatment plan
  • The U.S. tablet label advises no breastfeeding during treatment and for one week after the final dose

Alcohol

  • Avoid or minimize
  • Increases liver toxicity risk

Immunizations

  • Avoid live vaccines
  • Get flu and pneumonia vaccines

Monitoring

  • CBC (blood counts) every 2-4 weeks during titration, then every 2-3 months
  • Liver function tests (LFTs) on the same schedule; persistent elevation triggers a hold or dose change
  • Kidney function (creatinine, eGFR) at baseline and periodically - methotrexate is renally cleared and toxicity rises sharply when eGFR is <30
  • Baseline chest imaging in patients with prior lung disease; report any new cough, fever, or shortness of breath promptly (possible pneumonitis)
  • Hepatitis B and C screening, and latent TB screening, before starting
  • Symptoms of infection or toxicity at every visit
  • Visual acuity and exam to monitor disease activity

When to Contact Your Doctor

  • Fever or signs of infection
  • Severe nausea or vomiting
  • Mouth sores that don't heal
  • Unusual bruising or bleeding
  • Vision changes or new eye pain
  • Shortness of breath or persistent cough

References