Can a methotrexate (MTX) injection 29 days ago cause symptoms like sore throat, headache, body aches, runny nose, and stuffy nose?

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Methotrexate Side Effects 29 Days After Injection

No, your symptoms of sore throat, headache, body aches, runny nose, and stuffy nose are not likely side effects from a methotrexate injection received 29 days ago. These symptoms are more consistent with a viral upper respiratory infection rather than delayed methotrexate toxicity 1, 2.

Timing of Methotrexate Side Effects

Methotrexate side effects typically occur within a much shorter timeframe after administration:

  • Common early side effects (days to 1-2 weeks after administration):

    • Nausea, vomiting, fatigue, anorexia, stomatitis (mouth sores) 1
    • These typically occur shortly after medication initiation
  • Serious side effects that can occur with methotrexate include:

    • Myelosuppression (affecting blood counts)
    • Hepatotoxicity (liver damage)
    • Pneumonitis (lung inflammation)
    • Increased risk of infections 1, 2

Why Your Symptoms Are Likely Not Related to Methotrexate

  1. Timing: At 29 days post-injection, the methotrexate has been cleared from your system. Methotrexate is eliminated from the body within days, not weeks 3.

  2. Symptom pattern: Your symptoms (sore throat, headache, body aches, runny nose, stuffy nose) are classic signs of a viral upper respiratory infection rather than methotrexate toxicity 1.

  3. Methotrexate respiratory symptoms: When methotrexate affects the respiratory system, it typically causes pneumonitis with symptoms of progressive dyspnea (shortness of breath) and a dry cough, not upper respiratory symptoms like runny nose 1.

What Could Be Causing Your Symptoms

Your constellation of symptoms (sore throat, headache, body aches, runny nose, stuffy nose) is most consistent with:

  • Viral upper respiratory infection (common cold)
  • Seasonal allergies
  • Influenza
  • COVID-19

When to Seek Medical Attention

You should contact your healthcare provider if:

  • Symptoms persist beyond 7-10 days
  • You develop fever over 101°F (38.3°C)
  • You experience shortness of breath or difficulty breathing
  • Symptoms are severe or worsening

Important Considerations for Methotrexate Users

While your current symptoms are unlikely related to methotrexate, it's important to be aware of true methotrexate side effects:

  • Methotrexate can increase infection risk due to its immunosuppressive properties 1
  • Regular laboratory monitoring is recommended for patients on methotrexate therapy 1
  • Report persistent or concerning symptoms to your healthcare provider promptly

Remember that methotrexate is a potent medication with significant benefits for many conditions, but its side effect profile requires vigilance and proper monitoring.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

High-Dose Methotrexate Administration

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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