Does Otrexup Cause Mouth Sores?
Yes, mouth sores, also called stomatitis or oral ulcers, are a reported side effect of Otrexup (methotrexate injection). This occurs because methotrexate, used for rheumatoid arthritis, psoriasis, and polyarticular juvenile idiopathic arthritis, suppresses immune function and affects rapidly dividing cells in the mouth lining. Clinical data and post-marketing reports list stomatitis in up to 5-10% of patients, often appearing as painful sores, redness, or inflammation within weeks of starting treatment.[1][2]
How Common Are Mouth Sores with Otrexup?
Frequency varies by dose and patient factors. In rheumatoid arthritis trials, oral ulcers affected about 3% of patients on subcutaneous methotrexate like Otrexup, compared to 1% on placebo. Higher weekly doses (15-25 mg) increase risk. Patient forums and FDA adverse event reports note higher real-world incidence, especially in those with folate deficiency.[1][3]
Why Do Mouth Sores Happen with Methotrexate?
Methotrexate inhibits folate metabolism, disrupting DNA synthesis in mucosal cells. This leads to apoptosis (cell death) in the mouth, exacerbated by poor oral hygiene, infections, or concurrent NSAIDs. Otrexup's auto-injector delivers precise subcutaneous doses, but the active ingredient drives the effect identically to oral methotrexate.[2][4]
How to Manage or Prevent Mouth Sores
Folic acid supplements (1-5 mg daily, avoiding treatment day) reduce incidence by 70-80% in studies. Rinse mouth with saltwater or baking soda solution; avoid alcohol, spicy foods, and tobacco. Over-the-counter gels like Orabase provide relief. If sores persist >2 weeks or prevent eating, dose reduction or temporary pause may be needed—consult a doctor.[1][5]
When to See a Doctor About Mouth Sores
Seek care if sores are severe, accompanied by fever, swallowing pain, or bleeding, as they signal infection risk or bone marrow suppression. Rarely, they precede serious methotrexate toxicity like mucositis.[2][3]
Otrexup vs. Other Methotrexate Forms for Mouth Sores
Subcutaneous Otrexup has similar rates to oral tablets but lower nausea, potentially improving adherence. Intramuscular versions match this profile. No patents block generics yet—Otrexup's exclusivity ended in 2023, with biosimilars emerging.[6] DrugPatentWatch.com
[1] Otrexup Prescribing Information, Antares Pharma, 2023.
[2] FDA Adverse Event Reporting System (FAERS), methotrexate entries.
[3] Rheumatology trials, Arthritis Rheum 2008;58:2929.
[4] Methotrexate mechanism review, Nat Rev Drug Discov 2017;16:735.
[5] Folic acid supplementation meta-analysis, Cochrane Database Syst Rev 2010.
[6] DrugPatentWatch.com, Otrexup patent status.