Does Otrexup Cause Mouth Sores?
Yes, mouth sores are a reported side effect of Otrexup (methotrexate injection), occurring in up to 3% of patients in clinical studies. These are typically mild stomatitis or oral ulcers linked to methotrexate's impact on rapidly dividing cells in mucous membranes.[1][2]
How Common Are Mouth Sores with Otrexup?
Postmarketing data and clinical trials list stomatitis or mouth sores in 1-3% of users, more often with higher doses used for rheumatoid arthritis or psoriasis. Frequency rises with concurrent folic acid deficiency or alcohol use, which impair methotrexate clearance.[1][3]
Why Do Mouth Sores Happen?
Methotrexate inhibits dihydrofolate reductase, disrupting DNA synthesis in fast-growing tissues like the oral mucosa. Symptoms appear 3-7 days after dosing, resembling chemotherapy-induced mucositis. Folic acid supplementation reduces risk by 30-50%.[2][4]
How to Manage Mouth Sores from Otrexup
Rinse with saline or baking soda solution; use topical anesthetics like benzocaine. Avoid irritants like spicy foods or alcohol. Dose reduction or temporary pause resolves most cases within 1-2 weeks. Consult a doctor if sores persist or bleed.[1][3]
Are Mouth Sores More Likely with Otrexup Than Oral Methotrexate?
Similar incidence across formulations (1-5%), but Otrexup's subcutaneous delivery may cause less GI upset, indirectly lowering overall mucosal irritation. Patient reports note comparable oral side effects.[2][5]
When Should You Stop Otrexup for Mouth Sores?
Discontinue if severe (grade 3+ mucositis) or accompanied by fever/infection. FDA labeling advises holding doses for grade 2+ toxicity.[1]
[1]: Otrexup Prescribing Information (FDA)
[2]: Methotrexate Side Effects (Drugs.com)
[3]: RheumInfo on Methotrexate Stomatitis
[4]: Folic Acid and Methotrexate (Arthritis Foundation)
[5]: Otrexup vs Rasuvo Comparison (GoodRx)