Treating Back Pain with Naproxen and Baclofen
Direct Recommendation
For acute, non-radicular low back pain, use naproxen alone without adding baclofen, as the combination provides no additional functional benefit over naproxen monotherapy and increases the risk of central nervous system adverse effects. 1, 2
Evidence Against Baclofen for Low Back Pain
Baclofen is not indicated for low back pain. The FDA label explicitly states that baclofen is "not indicated in the treatment of skeletal muscle spasm resulting from rheumatic disorders" and is only approved for spasticity from multiple sclerosis and spinal cord diseases 3. Despite one older trial from 1985 showing modest benefit 4, more recent high-quality evidence demonstrates:
- A 2019 randomized trial of 320 patients found baclofen plus ibuprofen provided no improvement in Roland-Morris Disability Questionnaire scores compared to ibuprofen plus placebo (10.6 vs 11.1 point improvement) 2
- At 1-week follow-up, 33% of baclofen patients still reported moderate-to-severe pain versus 30% of placebo patients 2
- Baclofen has "sparse evidence" for low back pain despite efficacy in spasticity, according to American College of Physicians guidelines 5, 6
Recommended Treatment Approach
For Acute Low Back Pain (< 4 weeks):
Start with naproxen monotherapy at 500 mg twice daily as the first-line treatment 7, 8. NSAIDs provide moderate short-term pain relief with good evidence supporting their efficacy 7.
If muscle spasm is prominent and naproxen alone is insufficient, consider adding tizanidine (not baclofen) as the preferred muscle relaxant 9, 5, 6. Tizanidine combined with NSAIDs consistently provides greater short-term pain relief than NSAID monotherapy in high-quality trials 7, 5.
For Chronic Low Back Pain (> 12 weeks):
Avoid baclofen entirely 9. Instead:
- Continue naproxen 250-500 mg twice daily for the inflammatory component 7, 8
- Add a tricyclic antidepressant (amitriptyline) or duloxetine, which have moderate evidence for chronic pain 7, 9
For Radicular Pain (Sciatica):
Add gabapentin (1200-3600 mg/day) to naproxen for the neuropathic component, not baclofen 9, 5. Gabapentin shows small-to-moderate short-term benefits specifically for radiculopathy 7, 9.
Critical Safety Considerations
- All muscle relaxants increase CNS adverse events (sedation, dizziness) with a relative risk of 2.04 compared to placebo 5
- Limit muscle relaxant use to 1-2 weeks maximum for acute pain, as no evidence supports efficacy beyond 2 weeks 9, 6
- Tizanidine requires hepatotoxicity monitoring, though this is generally reversible 5, 6
- Naproxen dosing: Start 500 mg twice daily; maximum 1500 mg/day for up to 6 months in severe cases 8
Common Pitfalls to Avoid
- Do not combine naproxen with baclofen expecting enhanced benefit—recent high-quality trials show no advantage over monotherapy 1, 2
- Do not use benzodiazepines (like diazepam) as muscle relaxants—they show no benefit over placebo and carry abuse potential 7, 10
- Do not prescribe systemic corticosteroids—they are ineffective for low back pain with or without sciatica 7, 9
- Do not use muscle relaxants in elderly patients without careful fall risk assessment due to sedation 9
Why This Recommendation Differs from Older Practice
While a 1985 trial suggested baclofen benefit 4, the most recent and highest-quality evidence from 2019 directly contradicts this finding 2. The 2019 trial was larger (320 vs 200 patients), double-blind, placebo-controlled, and used validated functional outcomes. When prioritizing morbidity and quality of life outcomes, the 2019 evidence clearly demonstrates no functional benefit from adding baclofen to NSAIDs.