Adverse Effects of Low-Dose Methotrexate: A Randomized Trial

Ann Intern Med. 2020 Mar 17;172(6):369-380. doi: 10.7326/M19-3369. Epub 2020 Feb 18.


Background: Low-dose methotrexate (LD-MTX) is the most commonly used drug for systemic rheumatic diseases worldwide and is the recommended first-line agent for rheumatoid arthritis. Despite extensive clinical use for more than 30 years, few data on adverse event (AE) rates derive from randomized, placebo-controlled trials, where both causality and magnitude of risk can be inferred.

Objective: To investigate AE rates, risk, and risk differences comparing LD-MTX versus placebo.

Design: Prespecified secondary analyses of a double-blind, placebo-controlled, randomized trial. ( NCT01594333).

Setting: North America.

Participants: Adults with known cardiovascular disease and diabetes or metabolic syndrome.

Intervention: Random allocation to LD-MTX (≤20 mg/wk) or placebo. All participants received folic acid, 1 mg/d, 6 days per week.

Measurements: Risks for specific AEs of interest, as well as for all AEs, were compared across treatment groups after blinded adjudication.

Results: After an active run-in period, 6158 patients were enrolled and 4786 randomly assigned to a group; median follow-up was 23 months and median dosage 15 mg/wk. Among the randomly assigned participants, 81.2% were male, median age was 65.7 years, and median body mass index was 31.5 kg/m2. Of 2391 participants assigned to LD-MTX, 2080 (87.0%) had an AE of interest, compared with 1951 of 2395 (81.5%) assigned to placebo (hazard ratio [HR], 1.17 [95% CI, 1.10 to 1.25]). The relative hazards of gastrointestinal (HR, 1.91 [CI, 1.75 to 2.10]), pulmonary (HR, 1.52 [CI, 1.16 to 1.98]), infectious (HR, 1.15 [CI, 1.01 to 1.30]), and hematologic (HR, 1.15 [CI, 1.07 to 1.23]) AEs were elevated for LD-MTX versus placebo. With the exception of increased risk for skin cancer (HR, 2.05 [CI, 1.28 to 3.28]), the treatment groups did not differ in risk for other cancer or mucocutaneous, neuropsychiatric, or musculoskeletal AEs. Renal AEs were reduced in the LD-MTX group (HR, 0.85 [CI, 0.78 to 0.93]).

Limitation: The trial was done in patients without rheumatic disease who tolerated LD-MTX during an active run-in period.

Conclusion: Use of LD-MTX was associated with small to moderate elevations in risks for skin cancer and gastrointestinal, infectious, pulmonary, and hematologic AEs, whereas renal AEs were decreased.

Primary funding source: National Institutes of Health.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Video-Audio Media

MeSH terms

  • Aged
  • Antirheumatic Agents / administration & dosage*
  • Antirheumatic Agents / adverse effects*
  • Cardiovascular Diseases / drug therapy*
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Methotrexate / administration & dosage*
  • Methotrexate / adverse effects*
  • Middle Aged
  • Placebos
  • Prospective Studies


  • Antirheumatic Agents
  • Placebos
  • Methotrexate

Associated data